.
1
2014-2018
Past Papers & Mark Schemes
COMPILED BY: M.Mushtaq
03215275281
Hussain
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2
Cambridge International Examinations
Cambridge Ordinary Level
*3178912092*
COMPUTER STUDIES
7010/12
May/June 2014
Paper 1
2 hours 30 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 100.
This document consists of 24 printed pages.
IB14 06_7010_12/FP
© UCLES 2014
[Turn over
.
36
5
The following algorithm should:
•
•
•
input ten numbers
output the largest number input
output the average value of the input data
10
largest = 0
20
sum = 0
30
for x = 1 to 10
40
input x
50
if x > largest then x = largest
60
output largest
70
sum = sum + x
80
next x
90
average = sum * 10
100
output average
There are four errors in this algorithm.
Locate these errors and suggest a correction.
error 1
correction
error 2
correction
error 3
correction
error 4
correction
[4]
© UCLES 2014
7010/12/M/J/14
.
47
6
The following diagram shows six descriptions of automatic data capture methods and six terms.
Draw lines to connect each description to the correct term.
reading data directly from hard
copy and converting into electronic/
computer-readable form
biometrics
use of fingerprint scans, retina
scans, face identification, etc. as a
way of identifying a person
uniquely
data logging
recognises spoken word patterns
and compares them to patterns
stored in memory
optical
character
recognition
(OCR)
use of minute electronic devices
(containing microchip and antenna)
that can be read from distances up
to 5 metres
optical mark
recognition
(OMR)
automatic data collection using
sensors
radio
frequency
identification
(RFID)
system that reads pencil or pen
marks on a piece of paper in
pre-determined positions
voice
recognition
[5]
© UCLES 2014
7010/12/M/J/14
[Turn over
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10
5
8
In each case below, state which Internet term is being described.
(a) Malicious software installed on a user’s hard drive or a web server; the software re-directs
the user to a fake website without their consent or knowledge.
[1]
(b) Personal Internet journals where a writer enters text about a certain topic; anyone can
comment on the topic.
[1]
(c) Websites designed to promote the building of online communities who share the same
interests; usually free of charge; users can add friends, post messages to each other and
update personal profiles.
[1]
(d) Legitimate-looking email sent to a user in the hope of gathering personal information; as
soon as the recipient clicks on the link in the email (or email attachment) they are sent to a
fake website.
[1]
(e) Software that secretly gathers information by monitoring key presses on a user’s keyboard;
this information is relayed back to the person who sent the software originally.
[1]
© UCLES 2014
7010/12/M/J/14
.
12
6
10 Study the following flowchart.
START
count = 1
negcount = 0
poscount = 0
neg = 0
pos = 0
zero = 0
INPUT X
Yes
is X < 0 ?
neg = neg + X
negcount =
negcount + 1
pos = pos + X
poscount =
poscount + 1
No
Yes
is X > 0 ?
No
zero = zero + 1
count = count + 1
Yes
is count <=
10 ?
No
negavge = neg/negcount
posavge = pos/poscount
OUTPUT
negavge,
posavge, zero
© UCLES 2014
STOP
7010/12/M/J/14
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13
7
Complete the trace table for the flowchart using the following data:
0, 3, 5, 6, -4, -1, 0, 0, -4, 10
negcount poscount
neg
pos
zero
count
X
negavge
posavge
[6]
© UCLES 2014
7010/12/M/J/14
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16
8
13 An algorithm has been written to check that code numbers are valid on input. They must be in the
range 1000 to 9999.
Five hundred codes are being entered and the percentage of entered codes which are incorrect
is output.
There is a flowchart on the opposite page. It has some statements missing.
Complete the flowchart. Use statement numbers only, chosen from the list below.
© UCLES 2014
statement number
statement
1
Incorrect = Incorrect + 1
2
INPUT Code
3
is Number <= 500 ?
4
is Code < 1000 ?
5
is Code > 9999 ?
6
Number = 1
7
Number = Number + 1
8
OUTPUT Percent
9
Percent = Incorrect / 5
7010/12/M/J/14
.
17
9
START
incorrect = 0
Yes
No
Yes
No
Yes
No
STOP
[4]
© UCLES 2014
7010/12/M/J/14
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1200
16 An encryption system gives each letter of the alphabet a value:
A = 1, B = 2, C = 3, ……… , Y = 25, Z = 26.
Each letter is stored in a 12-bit binary register. The letter “S” (19th letter) is stored as:
2048 1024 512
0
0
0
256
128
64
32
16
8
4
2
1
0
0
0
0
1
0
0
1
1
A 4-bit register is used to store the encryption key. This register shows how many places the bits
are shifted to the left in the 12-bit register when it is encrypted. So,
8
4
2
1
0
1
0
1
means each bit in the 12-bit register is shifted 5 places to the left and the register now becomes:
2048 1024 512
0
0
1
256
128
64
32
16
8
4
2
1
0
0
1
1
0
0
0
0
0
Therefore, the letter “S” would be transmitted with the 4-bit register and the 12-bit register as
follows:
0
1
0
1
0
0
1
0
0
1
1
0
0
0
0
0
(a) “W” is the 23rd letter of the alphabet.
(i) Show how this letter would be stored in the 12-bit register before encryption:
(ii) The 4-bit register contains the following value:
8
4
2
1
0
1
1
0
Show how the letter “W” is now stored in the 12-bit register in encrypted form:
[2]
© UCLES 2014
7010/12/M/J/14
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1211
(b) Find which letter of the alphabet has been encrypted here. (Show all your working.)
0
0
1
1
0
0
0
0
1
1
0
0
1
0
0
0
[2]
(c) (i) What is the largest encryption key that can be stored in the 4-bit register?
8
4
2
1
(ii) Convert this into denary (base 10).
(iii) If this encryption key were used, what problem would it cause?
[3]
© UCLES 2014
7010/12/M/J/14
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1222
17 (a) Complete the truth table for the following logic circuit:
A
X
B
C
Working
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
X
[4]
© UCLES 2014
7010/12/M/J/14
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1233
(b) Write the logic statement to describe the following logic circuit:
A
X
B
C
[3]
© UCLES 2014
7010/12/M/J/14
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Page 3
3
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Mark Scheme
14
GCE O LEVEL – May/June 2014
Syllabus
7010
Paper
12
(a) 1 mark for naming software + 1 mark for a matching purpose
software:
purpose:
codec
– converts (and compresses) analogue data into digital data
software:
purpose:
(vide/audio) compression software
– reduces amount of (video/audio) data being transmitted
software
purpose:
echo cancellation software
– allows talking in real time
– prevents feedback/sound from speakers being picked up by microphone [4]
(b)
statement
advantage
it is possible to hold meetings at any time
there is no problem with time zones
reduces the “hidden cost” of employees being away from the office
[1]
(c) 1 mark for reason why each statement is incorrect:
– microphone only pick up sound/input device
– loudspeakers needed to produce the sound/voices for delegates to hear
– webcams do not record any data/video
– webcams (only) capture data/video
– webcams do not transmit data/video
[2]
(d) Any two from:
– expensive to set up
– poor quality of sound/video or need fast internet connection
– time zones can cause problems/differences in time zones
© Cambridge International Examinations 2014
[2]
4
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Mark Scheme
15
GCE O LEVEL – May/June 2014
Page 4
(a) Any one from:
Syllabus
7010
– search engine can pick up unrelated websites
– can result in too many “hits”
Paper
12
[1]
(b) Any one from:
– narrow down the search criteria
– e.g. chemistry transition element
– use of “…” around key words
(c) – pornographic/objectionable websites can be found
– unreliable/unnecessary information
– unwanted advertisements/pop-ups
[1]
[1]
(d) Any one from:
– faster/easier to do a search rather than looking at, e.g., several book indexes
– information more up-to-date
– can cut and paste information directly into a document
5
[1]
1 mark for identification of error and suggested correction (description or corrected pseudocode)
error:
correction:
number
line 40: input x; using same input value as loop variable will cause problems or line
30: for x = 1 to 10
change loop variable e.g. for count = 1 to 10 or change input variable e.g. input
error:
correction:
line 50: formula is reversed
…. then largest = x (or largest = number)
error:
correction:
line 60: output shouldn’t be inside the loop
100 output average, largest
error:
correction:
line 90: incorrect formula
average = sum/10
© Cambridge International Examinations 2014
[4]
Page 5
6
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Mark Scheme
16
GCE O LEVEL – May/June 2014
Syllabus
7010
Paper
12
1 mark for each correct link up to maximum of 5 marks
reading data directly from hard copy
and converting into electronic/
computer-readable form
biometrics
use of fingerprint scans, retina scans,
face identification, etc. as a way of
identifying a person uniquely
data logging
recognises spoken word patterns and
compares them to patterns stored in
memory
optical character
recognition (OCR)
use of minute electronic devices
(containing microchip and antenna)
that can be read from distances up to
5 metres
optical mark recognition
(OMR)
automatic data collection using
sensors
radio frequency
identification (RFID)
system that reads pencil or pen marks
on a piece of paper in pre-determined
positions
voice recognition
[5]
© Cambridge International Examinations 2014
9
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Mark Scheme
17
GCE O LEVEL – May/June 2014
Page 7
1 mark per point
Syllabus
7010
Paper
12
(i) key frames
(ii) tweening
(iii) morphing
(iv) rendering
(v) avars
[5]
10 (NOTES: Additional 0s in any column (UNLESS THEY ARE JUST THE REPEAT OF 0 VALUES)
lose the mark for that column
If columns 1 to 7 are wrong there can be one mark for initialisation (0 0 0 0 0 1) and a mark for
the correct output -3, 6).
negcount
poscount
neg
pos
zero
count
X
0
0
0
0
0
1
1
2
0
1
3
3
3
2
8
4
5
3
14
5
6
1
–4
6
–4
2
-5
7
–1
2
8
0
3
9
0
10
–4
11
10
3
–9
4
24
< - - - - - - 1 mark - - - - - > 1 mark
1 mark
negavge
posavge
–3
6
1 mark <- - - -1 mark - - - -> < - - - - - 1 mark - - - - >
[6]
© Cambridge International Examinations 2014
Page 10
13
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Mark Scheme
18
GCE O LEVEL – May/June 2014
Syllabus
7010
Paper
12
[4]
© Cambridge International Examinations 2014
.
Mark Scheme
19
GCE O LEVEL – May/June 2014
Page 11
Syllabus
7010
Paper
12
14 1 mark for each working formula in cells C3, C4, and C5.
A
B
C
1
input mass number
56
2
input atomic number
26
3
number of electrons =
= B2
4
number of protons =
= B2 (or = C3)
5
number of neutrons =
= B1 – B2
[3]
15 (a) 1 mark for each item:
–
–
–
–
–
–
knowledge base
rule(s) base
inference engine
(expert system) shell
explanation system
user interface/HCI
[4]
(b) Any one from:
–
–
–
–
–
–
–
chess/strategy games
prospecting for oil/minerals
medical diagnosis
engine diagnostics
television/computer/electronic diagnostics
financial/tax advice
career advice
[1]
16 (a) (i) 1 mark for correct binary numbers
0
0
0
0
0
0
0
1
0
1
1
1
1
0
0
0
0
0
0
(ii) 1 mark for correct binary numbers
0
1
0
1
1
[2]
© Cambridge International Examinations 2014
.
Mark Scheme
20
GCE O LEVEL – May/June 2014
Page 12
(b) one mark
– letter “Y” or 25th letter
Syllabus
7010
One mark
– the binary number 0 0 0 0 1 1 0 0 1 0 0 0 has been shifted (to the left) 3 places
– so the binary number becomes 0 0 0 0 0 0 0 1 1 0 0 1
– 1+8+16
Paper
12
[2]
(c) (i) 1 1 1 1
(ii) 15 (allow follow through from (i))
(iii) – try to move 15 places to the left which is not possible
– only 12 bits in register to store letter; 15 is too large
– you would end up with 12 0s in the register
[3]
17 (a)
A
B
C
X
0
0
0
1
0
0
1
1
0
1
0
0
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
0
1
1
1
0
1 mark
1 mark
1 mark
1 mark
[4]
S
© Cambridge International Examinations 2014
.
Mark Scheme
21
GCE O LEVEL – May/June 2014
Page 13
(b) ( A = NOT 1 )
Syllabus
7010
Paper
12
1 mark
OR
1 mark
(( A = 1 OR B = 1) AND C = 1 )
1 mark
Accept:
A
+
(( A + B ). C )
or
A
+
( A + B ). C
Accept:
A’
+
(( A + B ). C )
or
A’
+
( A + B ). C
(1 mark)
(1 mark)
(1 mark)
(NOT A)
OR
(( A OR B ).AND C )
(1 mark)
(1 mark)
(1 mark)
Accept:
[3]
18 marking points:
•
•
•
•
•
•
•
•
•
initialisation of all 5 totals
loop to control input for all 1500 students
input choice and name of student inside the loop
check student choice …
… increment the appropriate total
output name of student who likes classical music
find the 5 percentages (either using /15 or (*100/1500)) outside the loop
output the 5 percentages outside the loop (must have some processing)
error checking
© Cambridge International Examinations 2014
Page 14
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Mark Scheme
22
GCE O LEVEL – May/June 2014
sample algorithm (in pseudocode)
Syllabus
7010
Paper
12
NOTE: many students may make use of the case … of … endcase construct here rather than five IF
statements
rock = 0: soul = 0: pop = 0: jazz = 0: classical = 0
1 mark
for student = 1 to 1500
1 mark
input choice, pupil_name
if choice = 1 then rock = rock + 1
if choice = 2 then soul = soul + 1
if choice = 3 then pop = pop + 1
if choice = 4 then jazz = jazz + 1
if choice = 5 then classical = classical + 1
if choice = 5 then output pupil_name
next student
percent1 = rock/15
percent2 = soul/15
percent3 = pop/15
percent4 = jazz/15
percent5 = classical/15
output percent1, percent2, percent3, percent4, percent5
(sample pseudocode showing a possible case … of construct:
(alternative to rows 4 to 9 in above algorithm)
case of choice:
1: rock = rock + 1
2: soul = soul + 1
3: pop = pop + 1
4: jazz = jazz + 1
5: classical = classical + 1
output pupil_name
endcase)
© Cambridge International Examinations 2014
1 mark
2 marks
1 mark
1 mark
1 mark
2 marks
1 mark
[5]
.
23
Cambridge International Examinations
Cambridge Ordinary Level
* 8 8 5 0 4 1 6 5 8 5 *
7010/12
COMPUTER STUDIES
Paper 1
October/November 2014
2 hours 30 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
This document consists of 23 printed pages and 1 blank page.
DC (LEG/CGW) 100859
© UCLES 2014
[Turn over
.
244
4
Six statements and six values are shown below.
Each statement will generate one possible value.
Draw a line to link each statement to its correct value.
statement
value
number of times the following
loop operates:
count = 1
repeat
input x
count = count + 1
until count = 5
1
the number of bits that make up
a byte
base 10 (denary) value of the
following binary number:
32
16
8
4
2
1
0
0
1
1
1
1
4
5
8
the number of tracks on the
single side of a CD-R
number of minutes to upload a
75 Mbyte file at 2 megabits/
second upload speed
10
X
If there are 2 bytes in a Kbyte,
what is the value of X?
15
[5]
© UCLES 2014
7010/12/O/N/14
.
265
6
The following section of a pseudocode algorithm should:
•
•
•
•
input 500 numbers
generate a ratio called k
output each value of k
output how many numbers were larger than 10
10
20
30
40
50
60
70
80
total = 1
FOR x = 1 TO 500
IF number < 10 THEN total = total + 1
k = x / number
x = x + 1
OUTPUT k
NEXT x
OUTPUT x
(a) There are five errors in the above code.
Locate these errors and suggest a correction.
error 1 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 2 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 3 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 4 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 5 .......................................................................................................................................
correction ..................................................................................................................................
...............................................................................................................................................[5]
© UCLES 2014
7010/12/O/N/14
.
276
(b) The corrected algorithm was converted to a computer program and run. However, after
several numbers were input, the program stopped and an error message was generated,
showing that there was a further error at line 40 (k = x / number).
State what could cause this error to occur.
...................................................................................................................................................
...................................................................................................................................................
Suggest a change to line 40 to overcome this problem.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
© UCLES 2014
7010/12/O/N/14
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287
7
A digital camera contains a microprocessor. The camera’s specification includes:
•
•
•
20 megapixel resolution
32 gigabyte memory card
autofocus facility
(a) A more expensive model of the camera has 40 megapixel resolution.
(i)
Describe one advantage of increasing the resolution.
...........................................................................................................................................
.......................................................................................................................................[1]
(ii)
Describe one disadvantage of having 40 megapixel resolution.
...........................................................................................................................................
.......................................................................................................................................[1]
(b) (i)
Describe the type of memory used in the memory card.
...........................................................................................................................................
.......................................................................................................................................[1]
(ii)
Give one benefit of using this type of memory.
...........................................................................................................................................
.......................................................................................................................................[1]
(c) (i)
What is the meaning of the term pixel?
...........................................................................................................................................
.......................................................................................................................................[1]
(ii)
If a compressed image file requires an average of 1 byte per pixel, what is the maximum
number of photos that can be stored on the memory card?
...........................................................................................................................................
.......................................................................................................................................[1]
(d) Apart from autofocus, describe one other feature you would expect to see on a digital camera
controlled by a microprocessor.
...................................................................................................................................................
...............................................................................................................................................[1]
© UCLES 2014
7010/12/O/N/14
.
298
8
The doors on a train are opened and closed automatically. Motors are used to operate the doors.
The system is controlled by a microprocessor.
Each door has a sensor which detects if a passenger enters or leaves the train as the doors are
closing. If a passenger is detected, the doors are automatically re-opened.
(a) Name a sensor which could be used to detect a passenger.
...............................................................................................................................................[1]
(b) If the sensor in one of the doors fails, describe a safety mechanism to prevent injury to a
passenger.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[1]
(c) Describe how the sensors, microprocessor and door motors interact to ensure a passenger
is not trapped in a closing door.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
© UCLES 2014
7010/12/O/N/14
[Turn over
.
2129
10 (a) The flowchart on the next page shows how barcodes are used in a supermarket to find
product information and to produce orders for new stock automatically. Several statements
are missing from the flowchart.
Complete the flowchart, using item numbers only from the list below.
Item
number
© UCLES 2014
Description
1
is barcode found?
2
is barcode read?
3
is flag for this product = 1?
4
is number in stock <= re-order value?
5
key in the barcode manually
6
locate price and product information from file
7
output an error message
8
output order request for new stock
9
output receipt and itemised bill
10
reduce number in stock by 1 and write new value back to the record
11
search database for barcode
12
set flag for this product to 1
7010/12/O/N/14
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3130
START
No
any more
barcodes to
scan?
Yes
scan barcode
STOP
No
Yes
No
Yes
Yes
No
No
Yes
[8]
© UCLES 2014
7010/12/O/N/14
[Turn over
.
3161
12 An advertising sign uses large LED characters controlled by a microprocessor.
Each letter is formed from a grid made up of eight rectangles numbered 1 to 8:
1
2
3
4
5
6
7
8
For example, the letter “Z” is formed as follows:
1
2
4
5
7
8
Each rectangle has six LEDs that can light up; these LEDs are labelled “a” to “f”:
a
e
d
b
f
c
The LEDs in a rectangle can be represented in a 6-bit register. For example, rectangle 3 of the
letter “Z”:
a
e
can be represented as:
f
0
e
1
d
0
c
0
b
0
a
1
Thus the letter “Z” can be represented by the 8 registers:
1
5
© UCLES 2014
2
4
7
8
1
2
3
4
5
6
7
8
f
0
0
0
0
0
0
0
0
7010/12/O/N/14
e
0
0
1
0
0
1
0
0
d
0
0
0
0
0
0
0
0
c
0
0
0
0
0
1
1
0
b
0
0
0
0
0
0
0
0
a
0
1
1
0
0
0
0
0
.
3172
(a) Show how the letter “E” can be represented by the eight 6-bit registers (four registers have
been done for you).
f
e
d
c
b
a
0
0
0
0
0
0
1
2
3
1
2
3
4
5
6
7
8
0
0
0
0
0
0
4
0
0
0
0
0
0
5
6
7
0
0
0
0
0
0
8
[4]
(b) State which letter of the alphabet is represented by the following eight 6-bit registers.
f
e
d
c
b
a
0
0
0
0
0
0
1
0
0
1
0
0
0
2
0
0
0
0
1
0
3
0
0
0
0
0
0
4
0
0
0
0
0
0
5
0
0
1
0
0
1
6
0
0
0
0
1
1
7
0
0
0
0
0
0
8
letter ……………………………………
[2]
© UCLES 2014
7010/12/O/N/14
[Turn over
.
3183
13 (a) Complete the truth table for the following logic circuit:
A
B
X
C
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Working
X
[4]
© UCLES 2014
7010/12/O/N/14
.
3194
(b) Re-draw the logic circuit shown opposite, using NAND and NOR gates only.
[2]
(c) Write a logic statement that describes the following logic circuit:
A
B
X
C
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
© UCLES 2014
7010/12/O/N/14
[Turn over
.
3205
14 Study the following flowchart very carefully.
START
sum1 = 0
sum2 = 0
total = 0
INPUT a, b, c, d, e, f
Yes
is a = 0 and
b = 0?
STOP
No
sum1 = a*6 + b*5 + c*4
sum2 = d*3 + e*2 + f*1
total = sum1 + sum2
total = total – 11
is total = 0?
Yes
OUTPUT “data are OK”
No
No
© UCLES 2014
is total < 0?
Yes
7010/12/O/N/14
OUTPUT “error”
.
3216
Complete the trace table for this flowchart using the following data:
4, 3, 2, 0, 0, 8
5, 0, 1, 2, 3, 4
0, 0, 0, 0, 0, 0
sum1
sum2
total
a
b
c
d
e
f
OUTPUT
[5]
© UCLES 2014
7010/12/O/N/14
[Turn over
.
Mark Scheme
37
Cambridge O Level – October/November 2014
Page 3
4
Syllabus
7010
Paper
12
1 mark for each correct connection up to the maximum of 5
number of times the following loop
operates:
count = 1
repeat
input ×
count = count + 1
until count = 5
the number of bits that make up a
byte
base 10 (denary) value of the
following binary number:
32
0
16
0
8
4
1
1
2
1
1
number of minutes to upload a 75
Mbyte file at 2 megabits/second
upload speed
x
4
5
1
the number of tracks on single side
of a CD-R
If there are 2
1
8
10
bytes in a Kbyte,
15
what is the value of x?
[5]
© Cambridge International Examinations 2014
.
Mark Scheme
38
Cambridge O Level – October/November 2014
Page 4
5
(a)
Syllabus
7010
Paper
12
Sat Nav devices send signals to the global positioning
satellites
TRUE
Sat Nav accurately measures vehicle speed using satellite
position and accurate timing
TRUE
FALSE
Satellites tell the Sat Nav which direction the vehicle
should take
TRUE
FALSE
FALSE
FALSE
[3]
(b) Any two from:
–
–
–
6
software/maps not up to date/new road
loss of satellite signals
wrong data input by user (e.g. start point and end point)
[2]
(a) 1 mark for each error and suggested correction (accept description or example of corrected
pseudocode).
error:
correction:
line 10: total = 1
totals should be set to zero; total = 0
error:
correction:
line 30: … number < 10 …
check should be made if number > 10; … number > 10 …
error:
correction:
no input inside loop
input number
error:
correction:
line 50: x = x + 1
for … to loops don’t need a counter; remove line 50 altogether
error:
correction:
line 80: output x
output should be total value; output total
[5]
(b) division by zero error (or similar description of error produced when dividing by 0)
add an error trap after input of number
e.g. 40 if number = 0 then k = 0 else k = x/number
© Cambridge International Examinations 2014
[2]
7
.
Mark Scheme
39
Cambridge O Level – October/November 2014
Page 5
(a) (i) –
–
(ii) –
–
–
Syllabus
7010
higher quality photos
when “blown up” less likely for photo to “pixelate”
Paper
12
[1]
uses up more memory (on card)
takes longer to upload/download a photo
file size will be greater
[1]
(b) (i) –
–
–
(ii) –
–
–
(c) (i) –
(ii) –
solid state memory
flash drive
non-volatile
[1]
no moving parts (so more robust)
can be removed from camera and retain its contents
can erase contents and reuse memory card
[1]
(pic)ture (el)ement
[1]
819 or 1638
[1]
(d) Any one point from: e.g.
–
–
–
–
–
–
8
auto flash
anti (hand) shake facility
easy deletion of unwanted photos
ability to “manipulate” images after they have been taken/special effects
“smart” operation e.g. automatically pick out objects, faces, etc.
auto capture
[1]
(a) Any one from:
–
–
–
infra red (sensor)
pressure (sensor)
proximity (sensor)
[1]
(b) Any one from:
–
–
–
additional sensors used
door defaults to open position
sounds an alarm if a sensor fails
© Cambridge International Examinations 2014
[1]
.
Mark Scheme
40
Cambridge O Level – October/November 2014
Page 7
10 (a)
START
Syllabus
7010
Paper
12
No
any more
barcodes
to scan ?
Yes
9
scan barcode
(1 mark)
STOP
No
2
5
Yes
(1 mark)
11
(1 mark)
(1 mark)
No
1
7
Yes
6
(1 mark)
10
(1 mark)
Yes
4
(1 mark)
No
12
3
(1 mark)
No
Yes
8
[8]
© Cambridge International Examinations 2014
.
Mark Scheme
41
Cambridge O Level – October/November 2014
Page 8
Syllabus
7010
Paper
12
(b) 1 mark for each device + 1 mark for correct matching use
device:
use:
beeper/loud speaker
to indicate barcode correctly read/error in reading barcode
device:
use:
(LCD) screen/monitor
to show prices and other information about goods
device:
use:
touch screen
to show prices and other information about goods/to select items that need to be
weighed/identified
device:
use:
weighing machine
to find weight of loose items (e.g. fruit) to enable pricing
device:
use:
(magnetic) card reader/CHIP and PIN reader
to read customer’s debit/credit card/enable customer to pay for goods using a
credit or debit card
device:
use:
printer
to print receipts
(NOT keypad)
[4]
11 (a) = (B2/24) * B3
[1]
(b) = C4 * B5
[1]
(c) = IF (D1 < C6, “profit”, “no profit”) (NOTE: accept C6 > D1 in formula)
1 mark 1 mark
[2]
© Cambridge International Examinations 2014
.
Mark Scheme
42
Cambridge O Level – October/November 2014
Page 9
(d)
A
B
Syllabus
7010
C
D
1
1500
2
18
3
60
4
5
Paper
12
45
40
6
1800
1 mark
profit
1 mark
1 mark
[3]
12 (a) 1 mark for each of four rows shown in bold below; there are two possible ways of doing this –
one set of answers is shown on the left and the alternative is shown on the right in brackets.
Don’t allow mix and match; answers must either be as shown on the left OR as shown on the
right
0 0 0 0 0 0
0 0 1 0 0 1
(OR 0 0 1 1 0 1)
– 1 mark
0 0 0 0 0 1
(OR 0 0 0 1 0 1)
– 1 mark
0 0 1 1 0 1
(OR 0 0 1 1 0 0)
– 1 mark
0 0 0 1 0 1
(OR 0 0 0 1 0 0)
– 1 mark
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 0
[4]
(b) 2 marks for identifying the letter
letter: H
[2]
© Cambridge International Examinations 2014
.
Mark Scheme
43
Cambridge O Level – October/November 2014
Page 10
13 (a)
A
B
C
X
0
0
0
0
0
0
1
0
0
1
0
1
0
1
1
1
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
1
Syllabus
7010
Paper
12
1 mark
1 mark
1 mark
1 mark
[4]
(b) 1 mark per correct NOR gate and NAND gate on the left (ONLY accept two-input gates)
A
1 mark
X
B
1 mark
C
[2]
(c) 1 mark per logic statement as shown below:
(A = 1 AND B = 1) OR (B = NOT 1 AND C = 1)
(1 mark)
(1 mark)
(1 mark)
The above can be written as:
(A AND B) OR (NOT B AND C)
(1 mark) (1 mark) (1 mark)
Note: allow 1st part of formula and 2nd part of formula to be reversed:
(e.g. (NOT B AND C) OR (A AND B))
Also accept Boolean algebra:
b .c
a.b
+
(1 mark) (1 mark) (1 mark)
(can be written as: A.B + B.C)
© Cambridge International Examinations 2014
[3]
.
Mark Scheme
44
Cambridge O Level – October/November 2014
Page 11
Syllabus
7010
Paper
12
14 NOTE: sum1, sum2 and total MUST be initialised for all three inputs to get the mark; allow
repetition in any of the columns EXCEPT the OUTPUT column (e.g. sum1 can be 0, 47, 47, 47,
47, 47, 47);
sum1
sum2
total
a
b
c
d
e
f
0
0
0
4
3
2
0
0
8
47
8
55
OUTPUT
44
33
22
11
0
0
0
0
34
16
50
data are
OK
5
0
1
2
3
4
39
28
17
6
-5
error
0
0
0
0
0
0
0
0
0
1 mark
1 mark
1 mark < - - - - - - - - - - - - - - - - - 1 mark - - - - - - - - - - - - - - - >
1 mark
[5]
15 1 mark per feature applied to text in question:
taxi
cabs
– search and replace feature/retype/thesaurus
yelow
yellow
– spell checker/retype/auto-correct
changed
replaced
– search and replace feature/retype/thesaurus
translate last sentence/line
– (auto-)translator English to Spanish/other language
[4]
© Cambridge International Examinations 2014
Page 12
16 marking points:
•
•
•
•
•
•
•
•
.
Mark Scheme
45
Cambridge O Level – October/November 2014
Syllabus
7010
Paper
12
initialise highest value (zero or less)
loop control for all 3000 students
set total = 0 (to find the average) before second loop
loop control for all 8 exams
check if input mark higher than stored highest mark
if input mark higher, then set highest to this new value
find the average mark for each student (includes correct total addition)
both outputs in the correct place
(average after inside loop, highest outside outer loop)
(must be an attempt to find both average and highest to earn this mark)
sample program:
highest = -1
for student = 1 to 3000
total = 0
for exam = 1 to 8
input mark
total = total + mark
if mark > highest then highest = mark
next
average = total/8
output average
next
output highest
1 mark
1 mark
1 mark
1 mark
2 marks
1 mark
1 mark
© Cambridge International Examinations 2014
[5]
.
46
Cambridge International Examinations
Cambridge Ordinary Level
* 4 5 1 3 7 5 4 9 8 7 *
7010/13
COMPUTER STUDIES
Paper 1
October/November 2014
2 hours 30 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
This document consists of 22 printed pages and 2 blank pages.
DC (LK/CGW) 100855
© UCLES 2014
[Turn over
.
457
5
Six statements and six values are shown below.
Each statement will generate one possible value.
Draw a line to link each statement to its correct value.
statement
value
number of possible binary input
combinations for a 2-input logic
gate circuit
0
output from the logic gate:
1
1
1
base 10 (denary) value of the
following binary number:
4
2
1
1
1
0
4
what is the output from the
algorithm:
y=1
for x = 1 to 4
y=y*x
next x
print y
6
number of bytes formed from
8 bits
20
If there are 2X bytes in a Mbyte,
what is the value of X?
24
[5]
© UCLES 2014
7010/13/O/N/14
[Turn over
.
468
6
The following pseudocode algorithm should:
• input up to 20 numbers
• stop if the sum of the input numbers exceeds 50
• output the final sum
10
20
30
40
50
60
70
80
count = 0
REPEAT
INPUT n
n + sum = sum
IF sum = 50 THEN count = 20
count = count + 1
UNTIL count = 20
OUTPUT n
There are five errors in this algorithm.
Locate these errors and suggest a correction.
error 1 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 2 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 3 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 4 .......................................................................................................................................
correction ..................................................................................................................................
...................................................................................................................................................
error 5 .......................................................................................................................................
correction ..................................................................................................................................
...............................................................................................................................................[5]
© UCLES 2014
7010/13/O/N/14
.
489
8
Data sent across the Internet are frequently encrypted. The following flowchart shows a basic
encryption method (Note: the → symbol in the flowchart means “is replaced by”).
START
INPUT
character
is character =
“.” ?
Yes
STOP
No
is character a
vowel ?
Yes
a
e
i
o
u
A
A
A
A
A
o
u
a
e
i
b
c
d
f
g
h
j
A
A
A
A
A
A
A
s
t
v
w
x
y
z
k
l
m
n
p
q
r
A
A
A
A
A
A
A
b
c
d
f
g
h
j
s
t
v
w
x
y
z
A
A
A
A
A
A
A
k
l
m
n
p
q
r
No
is character =
b,c,d,f,g,h or j ?
Yes
No
is character =
k,l,m,n,p,q or r ?
Yes
No
No
© UCLES 2014
is character =
s,t,v,w,x,y or z ?
Yes
7010/13/O/N/14
.
590
For example,
l o
i
a m
a
r o b o t
.
y u c c e
a
o d
o
j e s e l
.
h e l
becomes:
(a) Use the flowchart to encrypt the following message:
m e e t
i n g
w i
l
l
g o
a h e a d .
[2]
(b) Use the information in the flowchart to show which input message produced the following
encrypted message:
t e d g i
l a f x
a k
w i
f
.
[2]
(c) Many customers shop online.
Apart from encryption, describe three other security features built into many online shopping
websites.
1 ................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
3 ................................................................................................................................................
...............................................................................................................................................[3]
© UCLES 2014
7010/13/O/N/14
[Turn over
.
5101
9
A cinema (movie theatre) uses automatic machines to allow customers to select tickets for movie
shows. Payments are made by credit or debit card.
(a) Identify two input devices which could be used by the cinema.
For each device, describe what it is used for.
input device 1 ............................................................................................................................
use ............................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
input device 2 ............................................................................................................................
use ............................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
(b) Identify two output devices which could be used by the cinema.
For each device, describe what it is used for.
output device 1 ……………………………………………………………………………………
use ............................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
output device 2 .........................................................................................................................
use ............................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
© UCLES 2014
7010/13/O/N/14
.
5112
10 A microwave oven cooks food when the food is placed on a rotating plate and the door is closed.
The oven is controlled by a microprocessor.
(a) Name two sensors that could be used in the microwave oven.
1 ................................................................................................................................................
2 ............................................................................................................................................[2]
(b) Describe two items of data that the user would need to input before pressing the start button.
Describe how these data could be input.
data 1
...................................................................................................................................................
...................................................................................................................................................
method of input 1
...................................................................................................................................................
...................................................................................................................................................
data 2
...................................................................................................................................................
...................................................................................................................................................
method of input 2
...................................................................................................................................................
.............................................................................................................................................. [4]
(c) Describe the role of the microprocessor in the microwave oven.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [4]
© UCLES 2014
7010/13/O/N/14
[Turn over
.
5123
11 An algorithm has been written to input six temperatures for every day of the year (365 days). The
outputs are:
• the average daily temperature for each day
• the highest recorded temperature for the whole year
The algorithm is in the form of a flowchart on the next page. However, several of the statements
are missing.
Using instruction number only, complete the flowchart using the following list of instructions:
Instruction
number
© UCLES 2014
Instruction
1
average = total / 6
2
day = day + 1
3
high = -200
4
high = temperature
5
input temperature
6
is reading <= 6 ?
7
is temperature > high ?
8
output average
9
output high
10
reading = reading + 1
11
total = 0
12
total = total + temperature
7010/13/O/N/14
.
5134
START
day = 1
reading = 1
Yes
No
Yes
No
STOP
Yes
is day <=
365 ?
No
[6]
© UCLES 2014
7010/13/O/N/14
[Turn over
.
5165
13 Study the following flowchart very carefully.
START
T1 = 0
T2 = 0
T3 = 0
INPUT A, B, C
is A = 0
and B = 0 and
C=0?
Yes
OUTPUT T1,
T2, T3
STOP
No
is A > B ?
Yes
No
is B > C ?
is A > C ?
No
No
T3 = T3 + 1
Yes
T2 = T2 + 1
© UCLES 2014
7010/13/O/N/14
Yes
T1 = T1 + 1
.
5176
(a) Complete the trace table for the flowchart using the following data:
3, 2, 1
T1
4, 8, 7
T2
6, 0, 3
T3
5, 6, 9
A
4, 11, 3
B
C
0, 0, 0
OUTPUT
[5]
(b) This flowchart does not give correct answers for certain sets of test data.
Suggest a data set that would give an incorrect answer.
Give a reason for your choice.
data set .....................................................................................................................................
...................................................................................................................................................
reason .......................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
© UCLES 2014
7010/13/O/N/14
[Turn over
.
5187
14 Digits on an electronic display board can be represented on a 7 × 5 grid. For example, the digit 3 is
represented as:
1 2 3 4 5
Row 1
Row 2
Row 3
Row 4
Row 5
Row 6
Row 7
Each column in the grid is represented in a computer as a 7-bit register. Five registers are required
to represent the state of the whole digit. The value 1 represents a shaded square and the value 0
represents an unshaded square. For example, the digit 3 is represented as:
Row number: 1 2 3 4 5 6 7
Register 1
Register 2
Register 3
Register 4
Register 5
0
1
1
1
0
1
0
0
0
1
0
0
0
0
1
0
0
1
1
0
0
0
0
0
1
1
0
0
0
1
0
1
1
1
0
(a) Show the contents of the five 7-bit registers when representing the digit 9:
1 2 3 4 5
1
2
3
4
5
6
7
Row number:
1
2
3
4
5
6
7
Reg 1
Reg 2
Reg 3
Reg 4
Reg 5
[4]
© UCLES 2014
7010/13/O/N/14
.
5198
(b) In order to prevent errors, an 8-bit register is used. The 8th bit will contain:
• 0 – if the first 7 bits add up to an even number
• 1 – if the first 7 bits add up to an odd number
Complete the 8th bit for each register. The first register has been completed for you.
1
2
3
4
5
6
7
8
Reg 1
0
1
0
0
0
1
0
0
Reg 2
1
0
0
0
0
0
1
Reg 3
1
0
0
1
0
0
1
Reg 4
1
0
0
1
0
0
1
Reg 5
0
1
1
0
1
1
0
[3]
© UCLES 2014
7010/13/O/N/14
[Turn over
.
5209
15 (a) Complete the truth table for the following logic circuit:
A
B
X
C
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Working
X
[4]
© UCLES 2014
7010/13/O/N/14
.
6210
(b) Re-draw the logic circuit shown opposite, using NAND and NOR gates only.
[2]
(c) Write a logic statement that describes the following logic circuit:
A
B
X
C
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
© UCLES 2014
7010/13/O/N/14
[Turn over
.
Mar
M k Sch
S hem
me
6e1
Cam
mbrridge
e O Le
eve
el – Oct
O tob
berr/N
Nov
vem
mb
ber 20
014
4
Pag
P ge 4
5
num
n
mbe
er of
o poss
p sible b
binary
y inputt
c mbin
com
nattion
ns for
f a2
2-inputt lo
ogic
c
g e ciircu
gate
uit
Sylllab
bus
7 10
701
Pape
er
13
0
o put fro
outp
om the
e lo
ogicc ga
ate:
1
1
1
base 10 (de
b
( nary) va
alue
e off the
fo
ollo
owing bin
nary
y num
n mbe
er:
4
2
1
1
1
0
4
wha
w
at iss th
he out
o tputt fro
om
m the
a orith
algo
hm
m:
y=1
fo
or x = 1 to
t 4
y=y*x
ne
extt x
p nt y
prin
6
n mbe
num
er of
o byte
b es form
f med frrom
m 8 bitts
20
0
Iff there
e arre 2
x
by
yte
es in
n a Mbytte,
24
4
w at iss th
wha
he valu
v ue of x?
1 mar
m rk fforr ea
ach
h co
orrrec
ct line (m
max
x 5)
5
[5
5]
© Ca
amb
brid
dge
e In
nterrnattion
nal Ex
xam
mina
atio
ons
s 20
014
4
.
Mark Scheme
62
Cambridge O Level – October/November 2014
Page 5
6
Syllabus
7010
Paper
13
1 mark for each error located with corresponding correction (description or corrected pseudocode
acceptable)
error:
correction:
line 10: sum not initialised
sum = 0
error:
correction:
line 40: incorrect formula for sum
sum = sum + n
error:
correction:
line 50: incorrect IF statement
IF sum > 50 THEN ……
error:
correction:
lines 50 and 60: value of count causes a problem e.g. loop never ending
either count = 19 on line 50
or
count = count + 1 between lines 30 and 40
or
any other correct solution
error:
correction
line 80: output of n is incorrect
output sum or print sum
[5]
7
(a) wikis
[1]
(b) social networking sites
[1]
(c) podcasts
[1]
(d) tagging
[1]
(e) blogs
[1]
8
(a)
duul a f x
na c c
< - - - - - - - - - - - - - - 1 mark - - - - - - - - - - - - - ->
x e
oy uov .
<- - - - - - - - - - 1 mark - - - - - - - - ->
[2]
(b)
c o m p u t i n g
<- - - - - - - - - - - - - 1 mark - - - - - - - - - - - - ->
i s
f u n .
<- - - - - - - - - 1 mark - - - - - - - - ->
[2]
© Cambridge International Examinations 2014
.
Mark Scheme
63
Cambridge O Level – October/November 2014
Page 6
(c) Any three from:
–
–
–
–
–
–
–
–
–
–
–
Syllabus
7010
Paper
13
customers need a password / PIN
use of card readers / use of Transaction Authentication Number (TAN)
only certain characters from password / PIN requested…
…the requested characters change each time user logs on
card security code requested
use of drop down boxes
use of a customer reference number
inform customer when they last logged on to the website
use of image verification code e.g. CAPTCHA
make reference to something unique to the customer e.g. their mobile phone number
use of secure protocol e.g. https, padlock symbol
[3]
9
(a) 1 mark for input device + 1 mark for its matching use
input device:
use:
touch screen
select film / cinema seats / price
input device:
use:
keyboard / keypad
input number of tickets / card PIN
input device:
use:
magnetic stripe reader / chip and PIN reader / card reader
reading credit / debit card details
input device:
use:
scanner
to read any promotional vouchers (etc.)
[4]
(b) 1 mark for each different output device + 1 mark for its matching use
output device: screen / monitor
use:
show films available / seating plan / prices of each seat / payment details
output device: printer
use:
print receipt / tickets
output device: loudspeaker / beeper
use:
to indicate error in input / confirmation of keys pressed
[4]
10 (a) 1 mark for each different sensor (max 2)
– pressure sensor
– example of sensor to detect if door closed / open e.g. magnetic field sensor, proximity
sensor
– moisture / humidity sensor
– temperature / infrared sensor
[2]
© Cambridge International Examinations 2014
.
Mark Scheme
64
Cambridge O Level – October/November 2014
Page 7
(b) 1 mark for each item of data (max 2):
–
–
–
–
–
–
–
Syllabus
7010
Paper
13
is the food frozen / uncooked / cooked?
cooking time
start / end time
power
weight
type of food
additional cooking feature e.g. browning
1 mark for each corresponding input method (max 2):
– turn dial to select option
– touch screen / buttons / concept keyboard / keypad to select options
– use of barcode readers (to read barcodes on food packaging which stores an automatic
cooking programme)
[4]
(c) Any four from:
– (microprocessor) checks / receives readings / data / signals from sensors….
– …..continuously
– if door open, (microprocessor) sends signal to sound alarm / stop process
– (microprocessor) compares weight of food against stored values…
– …and automatically sets cooking time / power
– cooking time controlled by (microprocessor) comparing with stored values
– (microprocessor) sends signal to beeper / notify when cooking program complete
[4]
© Cambridge International Examinations 2014
Page 8
.
Mark Scheme
65
Cambridge O Level – October/November 2014
11
Syllabus
7010
Paper
13
START
3
day = 1
11
(1 mark)
reading = 1
5
(1 mark)
Yes
4
7
No
10/12
(1 mark)
12/10
Yes
6
1
No
(1 mark)
1
8
(1 mark)
2
Yes
STOP
No
is days
<= 365 ?
9
(1 mark)
[6]
1
© Cambridge International Examinations 2014
.
Mark Scheme
66
Cambridge O Level – October/November 2014
Page 9
12 (a) (i) B3 / B2
Syllabus
7010
Paper
13
(1 mark)
(ii) (B5 / C4) * 2 or = ((B5 * B2) / B3) * 2
(1 mark)
[2]
(b) = IF(C6>D1, “above”, “equal or below”)
1 mark 1 mark
OR
= IF(D1<C6, “above”, “equal or below”)
1 mark 1 mark
Alternative word(s) for “above” are acceptable.
[2]
(c) C4, C6, D6
[1]
© Cambridge International Examinations 2014
.
Mark Scheme
67
Cambridge O Level – October/November 2014
Page 10
13 (a)
T1
T2
T3
0
0
0
Syllabus
7010
A
B
C
3
2
1
4
8
7
6
0
3
5
6
9
4
11
3
0
0
0
Paper
13
OUTPUT
1
1
2
1
2
2, 2, 1
1 mark
1 mark
1 mark
< - - - - - - - - - - 1 mark - - - - - - - - - - - ->
1 mark
If no marks are awarded for the columns then 1 mark can be given for correct initialisation of
T1, T2 & T3 as shown in the first row above.
[5]
(b) – any data set (except 0, 0, 0) where 2/3 of the numbers are the same e.g. 2, 8, 8
– flowchart does not allow for numbers which have the same value
[2]
© Cambridge International Examinations 2014
.
Mark Scheme
68
Cambridge O Level – October/November 2014
Page 11
14 (a) Row number:
1
2
3
Reg 1:
0
1
Reg 2:
1
Reg 3:
Syllabus
7010
4
5
6
7
1
0
0
0
0
0
0
1
0
0
1
1
0
0
1
0
1
0
Reg 4:
1
0
0
1
1
0
0
Reg 5:
0
1
1
0
0
0
0
Paper
13
Reg 1 + Reg 5 = 1 mark
Reg 2 = 1 mark
Reg 3 = 1 mark
Reg 4 = 1 mark
[4]
(b)
8
Reg 1:
0
Reg 2:
0
Reg 3:
1
Reg 4:
1
Reg 5:
0
Reg 2 + Reg 5 = 1 mark
Reg 3 = 1 mark
Reg 4 = 1 mark
[3]
© Cambridge International Examinations 2014
.
Mar
M k Sch
S hem
me
6e9
Cam
mbrridge
e O Le
eve
el – Oct
O tob
berr/N
Nov
vem
mb
ber 20
014
4
Pag
ge 12
1
15
5 (a)
(
A
B
C
X
0
0
0
0
0
0
1
0
0
1
0
0
0
1
1
1
1
0
0
0
1
0
1
0
1
1
0
0
1
1
1
1
Sylllab
S
bus
7 10
701
Pape
P
er
13
1m
mark
1m
mark
[4
4]
1m
mark
1m
mark
[4
4]
( ) 1m
(b)
marrk for
f corre
ect NO
OR
R ga
ate
e an
nd 1 ma
ark for corr
c rec
ct N
NAN
ND
D gate
e in
n co
orrrect positio
ons
s on
n le
eft
h nd sid
han
s de of
o dia
d agra
am
m.
A
X
B
C
[2
2]
[ A = NO
(
(c)
NOT 1 OR
R B = NOT
N T1]
A D
AN
[ B = 1 AN
AND C = NO
OT 1 ]
1 mar
m rk
1 mar
m rk
1 mar
m rk
O her no
Oth
otations wh
hic
ch are
a e accce
epttab
ble:
(NO
OT A OR
R NO
N T B)
B AN
AND (B
B AND
D NOT
N TC
C)
_ _
_
(A
A + B)
B . (B
B . C)
C
(A
A' + B')
B . (B . C')
[3
3]
© Ca
amb
brid
dge
e In
nterrnattion
nal Ex
xam
mina
atio
ons
s 20
014
4
Page 13
.
Mark Scheme
70
Cambridge O Level – October/November 2014
16 Marking points:
•
•
•
•
•
•
•
•
Syllabus
7010
Paper
13
initialise largest and two totals
control loop for 1000 items
check if price 1 > price 2 and increment total 1 (inside loop)
check if price 2 > price 1 and increment total 2 (inside loop)
calculate price difference (inside loop)
method of dealing with negative difference
check if calculated difference > largest difference and action taken if it is
three outputs OUTSIDE a loop (calculation must have been attempted)
Sample program in pseudocode:
largest = 0
smarket1 = 0: smarket2 = 0
for item = 1 to 1000
input price1, price2
if price1 > price2 then smarket1 = smarket1 + 1
if price2 > price1 then smarket2 = smarket2 + 1
difference = price1 – price2
if difference < 0 then difference = - difference
if difference > largest then largest = difference
next item
output smarket1, smarket2, largest
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
1 mark
(max 6)
[6]
© Cambridge International Examinations 2014
.
71
Cambridge International Examinations
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/01
For Examination from 2015
Paper 1 Theory
SPECIMEN PAPER
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
Calculators must not be used in this paper.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
This document consists of 14 printed pages.
© UCLES 2012
[Turn over
.
722
1
A company selling CDs uses a unique 6-digit identification number for each CD title. The rightmost digit (position 1) is a check digit.
For example,
digit position
identification number
6 5 4 3 2 1
3 0 6 1 4 9
check digit
The validity of the number and check digit is calculated as follows:
•
•
•
•
multiply each digit by its digit position
add up the results of the multiplications
divide the answer by 11
if the remainder is 0, the identification number and check digit are valid.
(a) Show whether the following identification numbers are valid or not. You must show how you
arrived at your answer.
Identification number 1: 4 2 1 9 2 3
working:
valid or not valid?
Identification number 2: 8 2 0 1 5 6
working:
valid or not valid?
© UCLES 2012
[3]
2210/01/SP/15
.
733
(b) Find the check digit for this identification number.
5 0 2 4 1 __
working:
check digit:
[2]
(c) Describe, with examples, two different types of data entry errors that a check digit would
detect.
1
2
[2]
2
Kamil is setting up a new computer system to record television programmes. He wants to be able
to record, view and then erase programmes that he does not want to keep. He has chosen to use
DVD-RAM as an optical storage medium.
Explain to Kamil why it is better to use DVD-RAM rather than DVD+RW or DVD-RW.
1
2
[2]
© UCLES 2012
2210/01/SP/15
[Turn over
.
744
3
An alarm, Y, sends a signal (Y = 1) when certain fault conditions in a chemical process are
detected. The inputs are:
Input
Binary value
Condition
1
acidity > 5
0
acidity <= 5
1
temperature >= 120UC
0
temperature < 120UC
1
stirrer bar ON
0
stirrer bar OFF
A
T
S
The alarm, Y, returns a value of 1 if:
either
temperature >= 120UC AND stirrer bar is OFF
or
acidity > 5 AND temperature < 120UC
(a) Draw the logic circuit for the above system using these logic gates.
NOT
AND
OR
A
Y
T
S
[5]
© UCLES 2012
2210/01/SP/15
.
755
(b) Complete the truth table for this alarm system.
A
T
S
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Y
[4]
© UCLES 2012
2210/01/SP/15
[Turn over
.
766
4
A digital alarm clock is controlled by a microprocessor. It uses the 24-hour clock system (i.e. 6 pm
is 18:00).
Each digit in a typical display is represented by a 4-digit binary code.
For example:
0
0
0
0
1st digit (0)
1
0
0
0
2nd digit (8)
0
0
1
1
3rd digit (3)
0
1
0
1
4th digit (5)
is represented by:
(clock display)
(a) What time is shown on the clock display if the 4-digit binary codes are:
0
0
0
1
0
1
1
0
0
1
0
0
1
0
0
1
(clock display)
[2]
(b) What would be stored in the 4-digit binary codes if the clock display time was:
1st digit
2nd digit
3rd digit
4th digit
[4]
© UCLES 2012
2210/01/SP/15
.
777
(c) The clock alarm has been set at 08:00.
Describe the actions of the microprocessor which enable the alarm to sound at 08:00.
[2]
5
Bytes of data transferred using a serial cable are checked for errors at the receiving end using an
even parity check.
Can these bytes of data pass the even parity check?
(a) 01010101
[1]
(b) 11001000
[1]
(c) How can any errors be corrected?
[2]
© UCLES 2012
2210/01/SP/15
[Turn over
.
788
6
The conditions in a fish tank are being controlled using sensors and a microprocessor. To keep
the fish healthy, the temperature must be at 25°C and the oxygen content needs to be 20 ppm
(parts per million). The tank contains a heater and an oxygen inlet controlled by a valve.
heater
oxygen supply
sensor A
sensor B
microprocessor
(a) Name the two sensors used in this application.
Sensor A
Sensor B
[2]
(b) Describe how the sensors and the microprocessor are used to maintain the correct
conditions in the fish tank.
[4]
(c) What safeguards are needed to stop the fish tank temperature rising too high?
[1]
© UCLES 2012
2210/01/SP/15
.
799
7
Ahmed uses the Internet for some time and is puzzled by the terminology.
(a) Draw a line to match each description to the appropriate technical term.
authoring language used to
create documents to be viewed
on the World Wide Web
Browser
computer that responds to
requests to provide information
and services over the Internet
HTML
defines how messages are
transmitted and formatted
over the Internet
MAC address
numerical ID for each device
on the Internet
Internet Server
software that enables users
to access/view documents and
other resources on the Internet
IP address
unique ID for a network
interface card
http
[5]
(b) Ahmed sees the message “Set your browser to accept cookies”.
Explain why some websites make this request.
[2]
© UCLES 2012
2210/01/SP/15
[Turn over
.
8100
8
Computer memories are measured in terms of the number of bytes.
(a) (i) What is meant by the term byte?
[1]
(ii) What is meant by the term Gigabyte?
[1]
(b) Flash memories and CD-RWs are used as backing media for computers.
Give two differences between these two media.
1
2
[2]
9
Andrew sends a large document to a printer.
(a) State the name for the area of memory used to store temporarily the data being sent to the
printer.
[1]
(b) The printer runs out of paper during the printing job. A signal is sent back to the computer to
stop temporarily its current task.
Name this type of signal.
[1]
© UCLES 2012
2210/01/SP/15
.
8111
10 In a simple symmetric encryption system, each letter of the alphabet is substituted with another.
The plain text message:
The quick brown fox jumps over the lazy dog.
becomes the cypher text message:
Zag towns jumpy dmh coilp mngu zag bfke qmx.
(a) (i) Decode this cypher text message.
Agbbm Pmubq
[2]
(ii) Convert these words to cypher text.
Computer Science
[2]
(b) Both the person who sends the message and the person who receives it need to know
what the substitution key is, and they need to keep this secret. A copy of the
substitution key has been sent using SSL transmission.
Explain why this keeps the copy of the key secret during transmission.
[2]
© UCLES 2012
2210/01/SP/15
[Turn over
.
8122
11 Five security or data loss issues are shown on the left-hand side.
Five possible methods of data recovery or protection are shown on the right.
Draw a line to match each definition/description of Issues to the most appropriate Methods of
Data Recovery.
Issues
Methods of Data Recovery
data loss caused by hard disk
head crash
anti-spyware software
hacking into files and changing
or deleting data
anti-virus software
introduction of software that
self-replicates and can cause
data loss
back-up files
reading of illegally accessed
documents
encryption
software that logs/records all
key presses on your computer
without you knowing
passwords and a firewall
[4]
© UCLES 2012
2210/01/SP/15
.
8133
12 Look at these two pieces of code:
A:
CLC
LDX
loop: LDA
ADC
STA
INX
CPX
BNE
#0
A,X
B,X
C,X
B: FOR Loop
INPUT
Sum =
PRINT
NEXT
= 1 TO 4
Number1, Number2
Number1 + Number2
Sum
#16
loop
(a) Which of these pieces of code is written in a high-level language?
[1]
(b) Give one benefit of writing code in a high-level language.
[1]
(c) Give one benefit of writing code in a low-level language.
[1]
(d) High-level languages can be compiled or interpreted.
Give two differences between a compiler and an interpreter.
1
2
[2]
© UCLES 2012
2210/01/SP/15
[Turn over
.
8144
13 When a key is pressed on the keyboard, the computer stores the ASCII representation of the
character typed into main memory.
The ASCII representation for A is 65 (denary), for B is 66 (denary), etc.
There are two letters stored in the following memory locations:
Location 1
B
Location 2
D
(a) (i) Show the contents of Location 1 and Location 2 as binary.
Location 1
Location 2
[2]
(ii) Show the contents of Location 1 and Location 2 as hexadecimal.
Location 1
Location 2
[2]
(b) The following machine code instruction is stored in a location of main memory:
1
1
0
1
1
0
1
1
1
0
0
1
1
1
1
1
Convert this binary pattern into hexadecimal.
[4]
(c) Explain why a programmer would prefer to see the contents of the locations displayed as
hexadecimal rather than binary, when debugging his program that reads the key presses.
[2]
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2012
2210/01/SP/15
.
825
1
(a) 1 mark for the correct working in BOTH parts
1 mark for valid
1 mark for not valid
Identification number 1: working
= (4 × 6) + (2 × 5) + (1 × 4) + (9 × 3) + (2 × 2) + (3 × 1)
= 24 + 10 + 4 + 27 + 4 + 3
= 72 ÷ 11
= 6 remainder 6
valid/not valid: NOT valid
Identification number 2: working
= (8 × 6) + (2 × 5) + (0 × 4) + (1 × 3) + (5 × 2) + (6 × 1)
= 48 + 10 + 0 + 3 + 10 + 6
= 77 ÷ 11
= 7 remainder 0
valid/not valid: VALID
[3]
(b) 1 mark for correct working + 1 mark for check digit
working
= (5 × 6) + (0 × 5) + (2 × 4) + (4 × 3) + (1 × 2)
= 30 + 0 + 8 + 12 + 2
= 52
need to add 3 to make the total 55 (i.e. exactly divisible by 11)
check digit: 3
[2]
(c) 1 mark for each description and example
2
–
–
2 digits transposed
(e.g. 280419 becomes 280149/two digits have been switched)
incorrect digit
(e.g. 280419 becomes 250419/one of the digits has been mistyped)
[2]
direct access because of concentric tracks
can read and write at the same time because it has a read/write head
[2]
© UCLES 2012
2210/01/SM/15
.
836
3
(a) 1 mark for each logic gate correctly connected
A
AND
NOT
Y
OR
T
AND
S
NOT
[5]
(b)
A
T
S
Y
0
0
0
0
0
0
1
0
0
1
0
1
0
1
1
0
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
0
}
]
]
]
]
1 mark
1 mark
1 mark
1 mark
[4]
4
(a) 1 mark for hours; 1 mark for minutes
1 6 : 4 9
1 mark 1 mark
[2]
(b) 1 mark for each digit
0
0
0
1
© UCLES 2012
0
1
0
0
0
1
1
0
1
1
0
1
1st digit
2nd digit
3rd digit
4th digit
[4]
2210/01/SM/15
[Turn over
.
847
5
(c) Any two from:
– microprocessor compares present time with stored time
– if the values are the same
– sends signal to sound alarm
[2]
(a) Yes
[1]
(b) No
[1]
(c) –
–
6
re-reading the byte that was sent
request that the byte is resent
[2]
(a) Only answers:
– temperature (sensor)
– oxygen (sensor)
[2]
(b) Any four from:
– information from the sensors sent to microprocessor
– the ADC converts the analogue data into digital form
– if temperature < 25ºC OR temperature checked against stored value
– ...microprocessor sends signal to heater/actuator/valve...
– ...to switch on heater
– if oxygen level < 20 ppm OR oxygen level checked against stored value
– ...to open valve/oxygen supply
– use of DAC between microprocessor and devices
– sounds an alarm if system unable to respond
– continuously monitors sensor inputs
– any reference to feedback
[4]
(c) Any one from:
– unsafe limit stored in memory
– warning sound/signal if too high a value reached
– fail safe switch off in case of a malfunction
[1]
© UCLES 2012
2210/01/SM/15
.
858
7
(a)
authoring language used to
create documents to be viewed
on the World Wide Web
Browser
computer that responds to
requests to provide information
and services over the Internet
HTML
defines how messages are
transmitted and formatted
over the Internet
MAC address
numerical ID for each device
on the Internet
Internet Server
software that enables users
to access/view documents and
other resources on the Internet
IP address
unique ID for a network
interface card
http
5/6 matches – 5 marks
4 matches – 4 marks
3 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
[5]
(b) any two from:
– to enable logon information to be kept on his computer
– to provide pages customised for Ahmed the next time he logs on
– to implement shopping carts and one-click purchasing
– to be able to distinguish between new and repeat visitors to the website
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8
(a) (i) Any one from:
– unit of data/memory
– 8 bits
– used to represent a character
(ii) Any one from:
– 230 bytes
– 1 073 741 824 bytes
– 1 048 576 kilobytes
– 1024 megabytes
[1]
[1]
(b) Any two from:
Flash memory
– solid state memory
– no formatting issues
– plugs directly into the USB port
– direct transfer of data
CD-RW
– optical media
– slower access speed/flash memory has faster access speed
– requires a separate drive
– data needs to be burnt/finalised/finished (before being used on another device)
9
[2]
(a) Any one from:
– buffer
– RAM
[1]
(b) –
[1]
interrupt
10 (a) 1 mark for each correct word
(i) Hello World
[2]
(ii) Nmilozgu Pnwgyng
[2]
(b) –
–
© UCLES 2012
use of Secure Socket Layer
the key itself is encrypted using strong encryption
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[2]
.
970
11
data loss caused by hard disk
head crash
anti-spyware software
hacking into files and changing or
deleting data
anti-virus software
introduction of software that
self-replicates and can cause
data loss
back-up files
reading of illegally accessed
documents
encryption
software that logs/records all
key presses on your computer
without you knowing
passwords and a firewall
5/4 matches – 4 marks
3 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
[4]
12 (a) code B
[1]
(b) Any one from:
– no need to understand workings of a computer
– easier to understand for programmer/closer to English
– much easier to debug
– much easier to test
– one-to-many when writing commands
– not machine-specific/portable
[1]
(c) Any one from:
– can address memory addresses directly
– no need for compilers/interpreters
– shorter code/code requires less storage/RAM
– can be written to run faster
[1]
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(d) –
–
–
–
–
compiler produces object code / interpreter doesn’t produce object code
compiler translates whole program in one go / interpreter translates and executes line at
a time
compiler produces list of all errors / interpreter produces error message each time an
error encountered
compiler produces “stand alone code” / interpreter doesn’t produce “stand alone code”
compilation process is slow but resultant code runs very quickly / interpreted code runs
slowly
[2]
13 (a) (i) 01000001
01000011
[2]
(ii) 41
43
[2]
(b) FA97
[4]
(c) –
–
[2]
© UCLES 2012
easier to identify values
easier to spot errors
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Cambridge International Examinations
Cambridge Ordinary Level
2210/02
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
For Examination from 2015
SPECIMEN PRE-RELEASE MATERIAL
No Additional Materials are required.
This material should be given to candidates up to six months before the examination.
READ THESE INSTRUCTIONS FIRST
Candidates should use this material in preparation for the examination. Candidates should attempt the
practical programming tasks using their chosen high-level, procedural programming language.
This document consists of 2 printed pages.
© UCLES 2012
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Candidates’ preparation for the examination should include attempting the following practical
program coding tasks.
Write and test a program to complete the three tasks.
TASK 1
Input and store the names and marks for 30 students who have sat three computer science tests.
Test 1 is out of 20 marks, Test 2 is out of 25 marks, Test 3 is out of 35 marks. You must store the
names in a one-dimensional array and the marks and total score for each student in one-dimensional
arrays. All the marks must be validated on entry and any invalid marks rejected. You may assume
that the students’ names are unique.
TASK 2
Calculate and store the total score for each student and calculate the average score for the whole
class. Output each student’s name followed by their total score, then output the average score for the
class.
TASK 3
Select the student with the highest score and output their name and score.
Your program must include appropriate prompts for the entry of data. Error messages and other
output need to be set out clearly and understandably. All variables, constants and other identifiers
must have meaningful names. Each task must be fully tested.
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2012
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Cambridge International Examinations
Cambridge Ordinary Level
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
2210/02
For Examination from 2015
SPECIMEN PAPER
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
Calculators must not be used in this paper.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
This document consists of 13 printed pages and 3 blank pages.
© UCLES 2012
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Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Section A Question 1.
Pre-release material
Write and test a program to complete the three tasks.
TASK 1
Input and store the names and marks for 30 students who have sat three computer science tests.
Test 1 is out of 20 marks, Test 2 is out of 25 marks, Test 3 is out of 35 marks. You must store the
names in a one-dimensional array and the marks and total score for each student in one-dimensional
arrays. All the marks must be validated on entry and any invalid marks rejected. You may assume
that the students’ names are unique.
TASK 2
Calculate and store the total score for each student and calculate the average score for the whole
class. Output each student’s name followed by their total score, then output the average score for the
class.
TASK 3
Select the student with the highest score and output their name and score.
Your program must include appropriate prompts for the entry of data. Error messages and other
output need to be set out clearly and understandably. All variables, constants and other identifiers
must have meaningful names. Each task must be fully tested.
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1
(a) All variables, constants and other identifiers should have meaningful names.
(i) Declare the array to store the students’ names.
[1]
(ii) Declare the arrays to store each student’s marks and total score.
[2]
(b) (i) Show the design of your algorithm to complete Task 1 and Task 2 using pseudocode,
programming statements or a flowchart. Do not include any of the validation checks in
your algorithm.
[8]
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(ii) Comment on the efficiency of your design.
[1]
(c) Show two different sets of student data that you could use to check the validation used in
Task 1. Explain why you chose each data set.
Set 1
Reason for choice
Set 2
Reason for choice
[2]
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(d) (i) Explain how you select the student with the highest score (Task 3). You may include
pseudocode or programming statements to help illustrate your explanation.
[5]
(ii) How does your program work when there is more than one student having the highest
score? Explain using your method given in part (d)(i).
[1]
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Section B
2
Jatinder uses Internet banking.
This pseudocode checks her PIN.
c ← 0
INPUT PIN
x ← PIN
REPEAT
x ← x/10
c ← c + 1
UNTIL x < 1
IF c <> 5
THEN
PRINT “error in PIN entered”
ELSE
PRINT “PIN OK”
ENDIF
(a) What value of c and what message would be output if the following PINs were entered?
5 1 0 2 0 Value of c:
Message:
5120
Value of c:
Message:
[2]
(b) What type of validation check is being carried out here?
[1]
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100
3
The flowchart inputs the size of a number of car engines; a value of –1 stops the input.
This information is output: average engine size and number of engines with size > 1.5
START
Engine ← 0
Count ← 0
Number ← 0
INPUT Size
is Size
= –1 ?
Yes
Average ← Engine/Number
OUTPUT
Average, Count
No
is Size
> 1.5 ?
Yes
STOP
Count ← Count + 1
No
Number ← Number + 1
Engine ← Engine + Size
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Complete the trace table for the input data.
1.8, 2.0, 1.0, 1.3, 1.0, 2.5, 2.0, 1.3, 1.8, 1.3,
Engine
Count
Number
Size
–1
Average
OUTPUT
[6]
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02
4
Read this section of program code that inputs twenty (20) numbers and then outputs the largest
number input.
1
h = 0
2
c = 0
3
REPEAT
4
READ x
5
IF x > h THEN x = h
6
c = c + 1
7
PRINT h
8
UNTIL c < 20
There are three errors in this code.
Locate these errors and suggest a corrected piece of code.
1
2
3
[3]
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03
6
(a) Write an algorithm, using pseudocode or flowchart only, which:
•
•
inputs three numbers
outputs the largest of the three numbers
[3]
(b) Write an algorithm, using pseudocode or flowchart only, which:
•
•
inputs 1000 numbers
outputs how many of these numbers were whole numbers (integers)
(You may use INT(x) in your answer, e.g. y = INT(3.8) gives the value y = 3)
[4]
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04
(c) Describe, with examples, two sets of test data you would use to test your algorithm.
1
2
[2]
7
A database was set up to show the properties of certain chemical elements. Part of the database
is shown below.
Name of
element
Element
symbol
Atomic
number
Atomic
weight
Melting
point (C)
Boiling
point (C)
State at
room temp
oxygen
O
8
16
–218
–183
gas
iron
Fe
26
56
1538
2861
solid
mercury
Hg
80
201
–38
356
liquid
bromine
Br
35
80
–7
59
liquid
osmium
Os
76
190
3033
5012
solid
caesium
Cs
55
133
28
671
solid
gallium
Ga
31
70
30
2204
solid
argon
Ar
18
40
–189
–186
gas
silver
Ag
47
108
961
2162
solid
(a) How many fields are in each record?
[1]
(b) The following search condition was entered:
(Melting point (C) < 40) AND (Atomic weight > 100)
Using Element symbol only, which records would be output?
[2]
(c) Which field would be best suited as primary key?
[1]
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Section A
1
(a) (i) Many correct answers, they must be meaningful. This is an example only.
StudentNames[1:30]
[1]
(ii) Many correct answers, they must be meaningful. This is an example only.
StudentMarksTest1[1:30]
StudentMarksTest2[1:30]
StudentMarksTest3[1:30] (1 mark)
StudentTotalScore[1:30] (1 mark)
[2]
(b) (i) –
–
–
–
–
–
–
–
outside loop zeroing total for loop (sum in example below)
loop for all students
input name and all test scores
in loop adding a student’s total
storing the total
inside loop printing student’s name and total
outside loop calculating class average
printing class average
sample algorithm:
Sum 0
FOR Count 1 TO 30
INPUT Name
StudentName[Count] Name
INPUT Mark1, Mark2, Mark3
StudentMarksTest1[Count] Mark1
StudentMarksTest2[Count] Mark2
StudentMarksTest3[Count] Mark3
Total Mark1 + Mark2 + Mark3
StudentTotalScore[Count] Total
Sum Sum + Total
PRINT StudentName[Count], StudentTotalScore[Count]
NEXT Count
ClassAverage = Sum/30
PRINT ClassAverage
(ii) any relevant comment with regards to efficient code (e.g. single loop)
(c)
[8]
[1]
Many correct answers, these are examples only.
1 mark per data set and reason
Set 1:
20, 25, 30, 35
Reason: valid data to check that data on the upper bound of each range check is
accepted
Set 2:
21, 26, 31, 36
Reason: invalid data to check that data above the upper bound of each range check is
rejected
[2]
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(d) (i) Maximum 5 marks in total for question part
Maximum 3 marks for algorithm
Description (max 3)
– set variable called HighestScore to zero and variable called BestName to dummy
value
– loop 30 times to check each student’s total score in turn
– check student’s score against HighestScore
– if student’s score > HighestScore then
– … replace value in HighestScore by student’s score and store student’s name in
BestName
– output BestName and HighestScore outside the loop
Sample algorithm (max 3):
HighestScore 0
BestName “xxxx”
FOR Count 1 TO 30
IF StudentTotalScore[Count] > HighestScore
THEN
HighestScore StudentTotalScore[Count]
BestName StudentName[Count]
ENDIF
NEXT Count
PRINT BestName, HighestScore
If algorithm or program code only, then maximum 3 marks
(ii) comment on which student(s)’ name will be output
e.g. The first student with the highest score will be output
© UCLES 2012
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(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
[5]
[1]
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107
Section B
2
(a) 1 mark for value of c and message
51020: value of c:
message:
5
PIN OK
(1 mark)
5120:
4
error in PIN entered
(1 mark)
value of c:
message:
[2]
(b) length check
[1]
3
Engine
Count
Number
Size
0
0
0
1.8
1.8
1
1
2.0
3.8
2
2
1.0
4.8
3
1.3
6.1
4
1.0
7.1
5
2.5
9.6
3
6
2.0
11.6
4
7
1.3
8
1.8
9
1.3
10
–1
12.9
14.7
5
16.0
Average
OUTPUT
1.6
(1 mark)
4
(1 mark)
(1 mark)
(1 mark)
(1 mark)
1.6, 5
(1 mark)
[6]
1 mark for each error identified + suggested correction
line 5:
this should read IF x > h THEN h = x
line 7:
PRINT h should come after the end of the repeat loop
line 8:
this should read UNTIL c = 20 or UNTIL c >= 20 or UNTIL c > 19
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108
6
(a) marking points:
the way to find and print the largest value a
the way to find and print the largest value b
the way to find and print the largest value c
sample algorithm:
INPUT a, b, c
IF a > b AND a > c THEN PRINT a
ELSE IF b > c THEN PRINT b
ELSE PRINT c
(b) marking points:
loop construct
check if number is an integer
counting the number of integers input
output count value (outside the loop)
sample algorithm:
FOR x ← 1 TO 1000
INPUT Number
Difference ← INT(number) – Number
IF Difference = 0 THEN Total ← Total + 1
NEXT x
PRINT total
(NOTE: alternative to lines 3 and 4:
IF INT(Number) = Number THEN Total ← Total + 1
1 mark
1 mark
1 mark
(1 mark)
(1 mark)
(1 mark)
[3]
1 mark
1 mark
1 mark
1 mark
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(2 marks) )
[4]
(c) Description of any two sets of test data. Many correct answers, these are examples only.
1000 whole numbers to ensure that loop works properly
900 whole numbers and 100 numbers with decimal places to ensure that the routine
distinguishes correctly
[2]
7
(a) 7
[1]
(b) Hg, Cs
[2]
(c) Element symbol
[1]
© UCLES 2012
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Cambridge International Examinations
Cambridge Ordinary Level
* 0 7 5 8 6 0 9 9 9 5 *
2210/11
COMPUTER SCIENCE
Paper 1 Theory
May/June 2015
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 15 printed pages and 1 blank page.
DC (LEG/CGW) 111631
© UCLES 2015
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110
1
(a) State what is meant by the terms:
Parallel data transmission .........................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Serial data transmission ...........................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
(b) Give one benefit of each type of data transmission.
Parallel data transmission
Benefit .......................................................................................................................................
...................................................................................................................................................
Serial data transmission
Benefit .......................................................................................................................................
...................................................................................................................................................
[2]
(c) Give one application of each type of data transmission. Each application must be different.
Parallel data transmission
Application ................................................................................................................................
...................................................................................................................................................
Serial data transmission
Application ................................................................................................................................
...................................................................................................................................................
[2]
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2
(a) State what is meant by the term USB.
...................................................................................................................................................
...................................................................................................................................................
[1]
(b) Describe two benefits of using USB connections between a computer and a device.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
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112
3
(a) Complete the truth table for the following logic circuit:
A
X
B
C
Workspace
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
X
[4]
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113
(b) Draw a logic circuit which corresponds to the following logic statement:
X = 1 if ((A is NOT 1 OR B is 1) AND C is 1) OR (B is NOT 1 AND C is 1)
A
B
X
C
[3]
(c) Write a logic statement which corresponds to the following logic circuit:
A
B
X
C
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
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114
4
Choose six correct terms from the following list to complete the spaces in the paragraphs below:
•
encryption
•
file name
•
firewall
•
HTML tags/text
•
IP address
•
protocol
•
proxy server
•
SSL certificate
•
web server name
A user enters a URL. The web browser breaks up the URL into three components:
1 ........................................................
2 ........................................................
3 ........................................................
The web server returns the selected web page.
The web browser reads the ............................................................ from the selected page and
shows the correctly formatted page on the user’s screen.
A ............................................................ is used between the user’s computer and the network to
examine the data traffic to make sure it meets certain criteria.
To speed up the access to the web pages next time, a ............................................................ is
used between the computer and web server; this device uses a cache to store the website home
page after it has been accessed for the first time.
[6]
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5
Five storage devices are described in the table below.
In column 2, name the storage device being described.
In columns 3, 4, or 5, tick () to show the appropriate category of storage.
1
2
Description of storage device
Name of
storage device
3
4
5
Category of storage
Primary
Secondary
Off-line
optical media which use one spiral
track; red lasers are used to read
and write data on the media surface;
makes use of dual-layering technology
to increase the storage capacity
non-volatile memory chip; contents of
the chip cannot be altered; it is often
used to store the start up routines in a
computer (e.g. the BIOS)
optical media which use concentric
tracks to store the data; this allows
read and write operations to be carried
out at the same time
non-volatile memory device which
uses NAND flash memories (which
consist of millions of transistors wired
in series on single circuit boards)
optical media which use blue laser
technology to read and write data on
the media surface; it uses a single
1.1 mm polycarbonate disc
[10]
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6
(a) Viruses, pharming and phishing are all examples of potential Internet security issues.
Explain what is meant by each of these three terms.
Virus .........................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Pharming ..................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Phishing ....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[6]
(b) An online bank requires a client to supply an 8-digit code each time they wish to access their
account on the bank’s website.
Rather than ask the client to use a keyboard, they are requested
to use an on-screen keypad (shown on the right) to input the
8-digit code.
The position of the digits on the keypad can change each time
the website is visited.
The client uses a mouse or touch screen to select each of the
8 digits.
(i)
2
5
1
6
8
3
9
0
4
7
Explain why the bank has chosen to use this method of entering the 8 digits.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
[2]
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(ii)
Name and describe another measure that the bank could introduce to improve the
security of their website.
Name .................................................................................................................................
Description ........................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
[2]
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18
7
(a) One of the key features of von Neumann computer architecture is the use of buses.
Three buses and three descriptions are shown below.
Draw a line to connect each bus to its correct description.
Bus
Description
address bus
this bus carries signals used
to coordinate the computer’s
activities
control bus
this bi-directional bus is used
to exchange data between
processor, memory and input/
output devices
data bus
this uni-directional bus carries
signals relating to memory
addresses between processor
and memory
[2]
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19
(b) The seven stages in a von Neumann fetch-execute cycle are shown in the table below.
Put each stage in the correct sequence by writing the numbers 1 to 7 in the right hand column.
The first one has been done for you.
Stage
Sequence
number
the instruction is then copied from the memory location contained
in the MAR (memory address register) and is placed in the MDR
(memory data register)
the instruction is finally decoded and is then executed
the PC (program counter) contains the address of the next instruction
to be fetched
1
the entire instruction is then copied from the MDR (memory data
register) and placed in the CIR (current instruction register)
the address contained in the PC (program counter) is copied to the
MAR (memory address register) via the address bus
the address part of the instruction, if any, is placed in the MAR
(memory address register)
the value in the PC (program counter) is then incremented so that it
points to the next instruction to be fetched
[6]
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20
8
An alarm clock is controlled by a microprocessor. It uses the 24 hour clock. The hour is represented
by an 8-bit register, A, and the number of minutes is represented by another 8-bit register, B.
(a) Identify what time is represented by the following two 8-bit registers.
A
128
64
32
16
B
8
4
2
1
128
64
32
16
8
4
2
1
0 0 0 1 0 0 1 0 : 0 0 1 1 0 1 0 1
Hours ............................................
Minutes .........................................
[2]
(b) An alarm has been set for 07:30. Two 8-bit registers, C and D, are used to represent the
hours and minutes of the alarm time.
Show how 07:30 would be represented by these two registers:
C
D
:
Hours
Minutes
[2]
(c) Describe how the microprocessor can determine when to sound the clock alarm.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
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(d) The LCD (liquid crystal display) on the clock face is back-lit using blue LEDs (light emitting
diodes). The brightness of the clock face is determined by the level of light in the room. The
amount of light given out by the LEDs is controlled by a control circuit.
Describe how the sensor, microprocessor and LEDs are used to maintain the correct
brightness of the clock face.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
(e) Modern LCD monitors and televisions use LED back-lit technology.
Give two advantages of using this new technology compared to the older cold cathode
fluorescent lamp (CCFL) method.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
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22
9 Draw a line to connect each question to the correct answer.
Answer
Question
What is the denary (base 10)
equivalent to the hexadecimal
digit E?
8
If 1 GB = 2x then what is the
value of X?
12
How many bits are there in one
byte?
14
If the broadband data download
rate is 40 megabits per second,
how many seconds will it take to
download a 60 MB file?
19
What is the denary (base 10)
value of the binary number
30
00100100?
What hexadecimal value
is obtained when the two
hexadecimal digits C and D
are added together?
36
[5]
© UCLES 2015
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23
10 Five statements about interpreters and compilers are shown in the table below.
Study each statement.
Tick () to show whether the statement refers to an interpreter or to a compiler.
Statement
Interpreter
Compiler
takes one statement at a time and executes it
generates an error report at the end of translation of the
whole program
stops the translation process as soon as the first error is
encountered
slow speed of execution of program loops
translates the entire program in one go
[5]
© UCLES 2015
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Cambridge O Level – May/June 2015
Page 2
(a) parallel
Syllabus
2210
Paper
11
any one from:
–
–
8 bits/1 byte/multiple bits sent at a time
using many/multiple/8 wires/lines
(1 mark)
serial
any one from:
–
–
one bit sent at a time
over a single wire
(1 mark)
[2]
(b) parallel
–
faster rate of data transmission
(1 mark)
serial
any one from:
–
–
–
more accurate/fewer errors over a longer distance
less expensive wiring
less chance of data being skewed/out of synchronisation/order
(1 mark)
[2]
(c) parallel
any one from:
–
–
sending data from a computer to a printer
internal data transfer (buses)
(1 mark)
serial
–
connect computer to a modem
© Cambridge International Examinations 2015
(1 mark)
[2]
2
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Cambridge O Level – May/June 2015
Page 3
(a) –
–
universal serial bus
description of USB
Syllabus
2210
Paper
11
[1]
(b) Any two from:
–
–
–
–
–
–
–
–
3
devices are automatically detected and configured when initially attached
impossible to connect device incorrectly/connector only fits one way
has become the industry standard
supports multiple data transmission speeds
lots of support base for USB software developers
supported by many operating systems
backward compatible
faster transmission compared to wireless
[2]
(a)
Working
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
X
1
0
0
0
0
1
1
1
] 1 mark
] 1 mark
] 1 mark
] 1 mark
[4]
© Cambridge International Examinations 2015
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Page 4
(b) 1 mark per dotted section
Syllabus
2210
Paper
11
A
B
X
C
[3]
(c) X is 1 if:
(A is 1 OR B is 1)
(1 mark)
AND
(1 mark)
(B is 1 OR C is NOT 1)
(1 mark)
accept equivalent ways of writing this:
e.g. (A OR B = 1)
AND (B OR NOT C = 1)
e.g. (A OR B)
AND (B OR NOT C)
e.g. (A + B) (B + C)
© Cambridge International Examinations 2015
[3]
4
.
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127
Cambridge O Level – May/June 2015
Page 5
1 mark per correct word
1
protocol
2
web server name
3
file name
Syllabus
2210
Paper
11
accept these three items in any order
HTML tags/text
firewall
proxy server
[6]
5
1 mark per device, 1 mark per category
Description of storage device
Name of
storage device
Category of storage
Primary
optical media which uses one spiral
track; red lasers are used to read and
write data on the media surface; makes
use of dual-layering technology to
increase the storage capacity
non-volatile memory chip; contents of
the chip cannot be altered; it is often
used to store the start-up routines in a
computer (e.g. the BIOS)
optical media which uses concentric
tracks to store the data; this allows read
and write operations to be carried out at
the same time
non-volatile memory device that uses
NAND flash memories (which consist of
millions of transistors wired in series on
single circuit boards)
DVD
DVD-RAM
Solid State
Drive/memory
(SSD)
Blue-ray
Off-line
ROM
(SD/XD card)
(USB storage
device)
optical media that uses blue laser
technology to read and write data on
the media surface; it uses a single 1.1
mm polycarbonate disc
Secondary
()
()
[10]
© Cambridge International Examinations 2015
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Page 6
6
(a) virus
Syllabus
2210
Paper
11
any two from:
–
–
–
program/software that replicates/copies itself
can delete or alter files/data stored on a computer
can make the computer “crash”/run slow
pharming
any two from:
–
–
–
malicious code/software installed on a user’s hard drive/actual web server
this code redirects user to a fake website (without their knowledge)
to obtain personal/financial information/data
phishing
any two from:
–
–
–
–
legitimate-looking emails sent to a user
as soon as recipient opens/clicks on link in the email/attachment …
… the user is directed to a fake website (without their knowledge)
To obtain personal/financial information/data
[6]
(b) (i) Any two from:
–
spyware/key logging software can only pick up key presses
–
using mouse/touchscreen means no key presses to log
–
the numbers on the key pad are in random/non-standard format,
which makes it more difficult to interpret
© Cambridge International Examinations 2015
[2]
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Syllabus
2210
Paper
11
(ii) 1 mark for name and 1 mark for description
any one from:
chip and PIN reader
– only the user and the bank know which codes can be generated
request user name
– additional security together with password/PIN
anti-virus
– removes/warns of a potential virus threat which can’t be passed on to
customers
firewall
– (helps) to protect bank computers from virus threats and hacking
encryption
– protects customer data by making any hacked information unreadable
security protocol
– governs the secure transmission of data
Biometric
– to recognise user through the use of, e.g. facial/retina/finger print
Alerts
– users IP/MAC address is registered and user is alerted through, e.g. SMS if
account is accessed through an unregistered address
[2]
7
(a)
this bus carries signals used to
coordinate the computer’s
activities
address bus
this bi-directional bus is used to
exchange data between
processor, memory and
input/output devices
control bus
this uni-directional bus carries
signals relating to memory
addresses between processor
and memory
data bus
2/3 matches – 2 marks
1 match – 1 mark
[2]
© Cambridge International Examinations 2015
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Page 8
(b)
Syllabus
2210
description of stage
Paper
11
sequence
number
the instruction is then copied from the memory location contained in the
MAR (memory address register) and is placed in the MDR (memory data
register)
3
the instruction is finally decoded and is then executed
7
the PC (program counter) contains the address of the next instruction to be
fetched
(1)
the entire instruction is then copied from the MDR (memory data register)
and placed in the CIR (current instruction register)
4
the address contained in the PC (program counter) is copied to the MAR
(memory address register) via the address bus
2
the address part of the instruction is placed in the MAR (memory address
register)
6
the value in the PC (program counter) is then incremented so that it points
to the next instruction to be fetched
5*
The incrementation of the program counter can appear at any stage after 2. All other
stages must be in the correct given order.
8
(a) hours:
[6]
18
minutes:
53
[2]
(b)
hours (“C”)
0
0
0
0
0
1
minutes (“D”)
1
1
:
0
0
0
1
1
1
1
0
[2]
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Page 9
(c) Any three from:
Syllabus
2210
Paper
11
–
reads values in registers “C” and “D”
–
and checks the values against those stored in registers “A” and “B”
(NOTE: the first two statements can be interchanged, i.e. “A” and “B” read first)
–
If values in corresponding registers are the same
–
the microprocessor sends a signal to sound alarm/ring
[3]
(d) Any three from:
–
uses a light sensor
–
sends signal/data back to microprocessor
–
signal/data converted to digital (using ADC)
–
value compared by microprocessor with pre-set/stored value
–
if value < stored value, signal sent by microprocessor …
–
… to the voltage supply (unit)
–
… “value” of signal determines voltage supplied/brightness of LED
[3]
(e) Any two from:
–
no need to warm up
–
whiter tint/more vivid colours/brighter image
–
higher resolution
–
much thinner monitors possible/lighter weight
–
more reliable technology/longer lasting
–
uses much less power/more efficient
© Cambridge International Examinations 2015
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Cambridge O Level – May/June 2015
Page 10
9
What is the denary (base 10)
equivalent to the hexadecimal
digit “E”?
x
If 1 GByte = 2
value of X?
then what is the
Syllabus
2210
8
12
The number of bits in one byte
14
If the broadband data download
rate is 40 megabits/ second; how
long will it take to download a 60
MByte file?
19
What is the denary (base 10)
value of the binary number:
0 0 1 0 0 1 0 0?
What hexadecimal value is
obtained when the two
hexadecimal digits, C and D, are
added together?
Paper
11
30
36
5/6 matches – 5 marks
4 matches – 4 marks
3 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
[5]
© Cambridge International Examinations 2015
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10 1 mark per correctly placed tick
statement
Syllabus
2210
interpreter
takes one statement at a time and executes it
compiler
generates an error report at the end of translation of the
whole program
stops the translation process as soon as the first error is
encountered
slow speed of execution of program loops
translates the entire program in one go
Paper
11
[5]
© Cambridge International Examinations 2015
.
134
Cambridge International Examinations
Cambridge Ordinary Level
* 9 4 7 0 5 3 9 2 0 0 *
2210/12
COMPUTER SCIENCE
Paper 1 Theory
May/June 2015
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 14 printed pages and 2 blank pages.
DC (RW) 111393
© UCLES 2015
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135
1
(a) Four statements about cookies are shown in the table below.
Study each statement.
Tick (✓) to show whether the statement is true or false.
Statement
True
False
they are a form of spyware
they are used only in advertising
they are used to track browser use
they act in the same way as a virus
[4]
(b) Five descriptions and five security issues are shown below.
Draw a line to connect each description to the correct security issue.
Description
Security issue
malicious code installed on the hard drive of a
user’s computer or on the web server; this code
will re-direct user to a fake web site without their
consent
hacking
software that gathers information by monitoring
key presses on a user’s computer and relays
the information back to the person who sent the
software
pharming
program or code that replicates itself and is
designed to amend, delete or copy data and files
on a user’s computer without their consent
phishing
the act of gaining illegal access to a computer
system without the owner’s consent
spyware
creator of code sends out a legitimate-looking
email in the hope of gathering personal and
financial data; it requires the recipient to follow a
link in the email or open an attachment
virus
[4]
© UCLES 2015
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2
The majority of mobile phones use touch screens. Three common technologies are used by
different mobile phone manufacturers.
Choose one of the following mobile phone technologies:
•
•
•
resistive
capacitive
infrared
Chosen technology ..........................................................................................................................
(i)
Describe how your chosen technology works to allow a user to make selections by touching
the screen.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(ii)
Give one benefit and one drawback of your chosen technology when used on mobile phone
touch screens.
Benefit
...................................................................................................................................................
...................................................................................................................................................
Drawback
...................................................................................................................................................
...................................................................................................................................................
[2]
© UCLES 2015
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137
3
Four input devices, four descriptions and four applications are shown below.
Draw a line to connect each input device to its correct description. Then connect each description
to its correct application.
Input device
Description
Application
barcode reader
copies paper documents and
converts the text and pictures
into a computer-readable form
voice
recognition
reads labels containing parallel
dark and light lines using laser
light or LEDs; the width of each
line represents a binary code
reading
passports
pH sensor
detects changes in acidity
levels; data is often in
analogue form
automatic stock
control
scanner
device that allows audio
signals to be converted into
electric signals; these can be
interpreted by a computer after
being converted into digital form
monitor soil in a
greenhouse
microphone
[6]
© UCLES 2015
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138
4
(a) State what is meant by the term SSL.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[1]
(b) The following stages take place when a user wishes to access a secure website.
Put each stage in sequence by writing the numbers 1 to 6 in the column on the right. The first
one has been done for you.
Sequence
number
Stage
the encrypted data is then shared securely between the web browser
and the web server
the web browser attempts to connect to a website which is secured by
SSL
1
the web server sends the web browser a copy of its SSL certificate
the web browser requests the web server to identify itself
the web server will then send back some form of acknowledgement to
allow the SSL encrypted session to begin
the web browser checks whether the SSL certificate is trustworthy; if it
is, then the web browser sends a message back to the web server
[5]
© UCLES 2015
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139
5
Parity checks are often used to check for errors that may occur during data transmission.
(a) A system uses even parity.
Tick (✓) to show whether the following three bytes have been transmitted correctly or
incorrectly.
Received byte
Byte transmitted correctly
Byte transmitted incorrectly
11001000
01111100
01101001
[3]
(b) A parity byte is used to identify which bit has been transmitted incorrectly in a block of data.
The word “F L O W C H A R T” was transmitted using nine bytes of data (one byte per
character). A tenth byte, the parity byte, was also transmitted.
The following block of data shows all ten bytes received after transmission. The system uses
even parity and column 1 is the parity bit.
letter
column column column column column column column column
1
2
3
4
5
6
7
8
byte 1
F
1
0
1
0
0
1
1
0
byte 2
L
1
0
1
0
1
1
0
0
byte 3
O
1
0
1
0
1
1
1
1
byte 4
W
1
0
1
1
0
1
1
1
byte 5
C
1
0
1
0
0
0
1
1
byte 6
H
0
0
1
0
1
0
0
0
byte 7
A
0
0
1
0
0
1
0
1
byte 8
R
1
0
1
1
0
0
1
0
byte 9
T
1
0
1
1
0
1
0
0
1
0
1
1
1
1
1
0
parity
byte
(i)
One of the bits has been transmitted incorrectly.
Write the byte number and column number of this bit:
Byte number ......................................................................................................................
Column number .................................................................................................................
[2]
© UCLES 2015
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140
(ii)
Explain how you arrived at your answer for part (b)(i).
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
(c) Give the denary (base 10) value of the byte: 1
0111110
...................................................................................................................................................
...............................................................................................................................................[1]
(d) A parity check may not identify that a bit has been transmitted incorrectly.
Describe one situation in which this could occur.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[1]
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141
6
A gas fire has a safety circuit made up of logic gates. It generates an alarm (X = 1) in response to
certain conditions.
Input
G
C
L
Description
Binary
value
Conditions
1
gas pressure is correct
0
gas pressure is too high
1
carbon monoxide level is correct
0
carbon monoxide level is too high
1
no gas leak is detected
0
gas leak is detected
gas pressure
carbon monoxide level
gas leak detection
The output X = 1 is generated under the following conditions:
gas pressure is correct AND carbon monoxide level is too high
OR
carbon monoxide level is correct AND gas leak is detected
(a) Draw a logic circuit for this safety system.
*
&
;
/
[5]
© UCLES 2015
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142
(b) Complete the truth table for the safety system.
Workspace
G
C
L
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
X
[4]
(c) Complete the truth table for the XOR gate:
A
B
0
0
0
1
1
0
1
1
C
[1]
© UCLES 2015
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43
7
(a) Street lighting is controlled automatically. A light sensor and a microprocessor are used to
decide when to switch each street light on or off.
Describe how the sensor, microprocessor and light interact to switch the street light on or off.
Include in your answer how the microprocessor stops the street lights being frequently
switched on and off due to brief changes in the light intensity.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
(b) Name three different sensors (other than light and pH) and describe an application for each
of these sensors.
A different application is needed for each sensor.
Sensor 1 ...................................................................................................................................
Application ................................................................................................................................
...................................................................................................................................................
Sensor 2 ...................................................................................................................................
Application ................................................................................................................................
...................................................................................................................................................
Sensor 3 ...................................................................................................................................
Application ................................................................................................................................
...................................................................................................................................................
[6]
© UCLES 2015
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44
8
Five computing terms are described below.
Write the name of the term being described.
Software that anyone can download for free from the Internet
and then use without having to pay any fees. The usual
copyright laws apply and a user license is important.
................................................
Software that gives the user the chance to try it out free of
charge before actually buying it. The software is subject to the
usual copyright laws. As a rule, not all the features found in the
full version are available at this stage.
................................................
Software where users have freedom to run, copy, change and
adapt it. This is an issue of liberty and not of price since the
software guarantees freedom and the right to study and modify
the software by having access to the actual source code.
................................................
Set of principles that regulates the use of computers in
everyday life. This covers intellectual property rights, privacy
issues and the effects of computers on society in general.
................................................
The taking of somebody’s idea or software and claim that the
idea or software code were created by the “taker”.
................................................
[5]
© UCLES 2015
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45
9
(a) Five statements about interpreters and compilers are shown in the table below.
Study each statement.
Tick (✓) to show whether the statement refers to an interpreter or to a compiler.
Statement
Interpreter
Compiler
creates an executable file that runs directly on the
computer
more likely to crash the computer since the machine
code produced runs directly on the processor
easier to debug since each line of code is analysed
and checked before being executed
slow speed of execution of program loops
it is more difficult to modify the executable code,
since it is in machine code format
[5]
(b) State why a compiler or an interpreter is needed when running a high-level program on a
computer.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[1]
(c) Give one benefit of writing a program in a high-level language.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[1]
(d) Give one benefit of writing a program in a low-level language.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[1]
© UCLES 2015
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46
(e) Study the following three sections of code.
A:
1 0 1 0 1 1 0 1
1 1 0 0 1 1 1 0
1 0 1 1 0 1 1 1
B:
LDA X
INC X
STA Y
C:
FOR x ← 1 TO 10
READ n
ENDFOR
Identify, using the letters A, B or C, which of the above codes is an example of assembly
code, high-level language code or machine code:
Assembly code .........................................................................................................................
High-level language code .........................................................................................................
Machine code ...........................................................................................................................
[2]
© UCLES 2015
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47
10 Letters from the alphabet are represented in a computer by the following denary (base 10) values:
A
G
I
L
N
The word “A L I G N” is stored as: 97
=
=
=
=
=
108
97
103
105
108
110
105
103
110
(a) Convert each of the five values to binary. The first one has been done for you.
Letter
A (97):
Denary value
0
1
1
0
0
0
0
1
L (108):
I (105):
G (103):
N (110):
[2]
(b) An encryption system works by shifting the binary value for a letter one place to the left. “A”
then becomes:
1
1
0
0
0
0
1
0
This binary value is then converted to hexadecimal; the hexadecimal value for “A” will be:
C
2
For the two letters “L” and “G”, shift the binary values one place to the left and convert these
values into hexadecimal:
hexadecimal
L:
.............................................
G:
.............................................
[4]
© UCLES 2015
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Page 2
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Mark Scheme
148
Cambridge O Level – May/June 2015
(a) 1 mark per correctly placed tick
Statement
Syllabus
2210
True
False
they are a form of spyware
they are used in advertising only
they are used to track the browsing of a user
they act in the same way as a virus
Paper
12
[4]
(b)
malicious code installed on the hard drive of a
user’s computer or on the web server; this code
will re-direct user to a fake web site without their
consent
hacking
software that gathers information by monitoring
key presses on a user’s computer and relays the
information back to the person who sent the
software
pharming
program or code that replicates itself and is
designed to amend/delete/copy data and files on
a user’s computer without their consent
phishing
the act of gaining illegal access to a computer
system without the owner’s consent
spyware
creator of code sends out a legitimate-looking
email in the hope of gathering personal and
financial data from the recipient; it requires the
email or attachment to be opened first
virus
4/5 matches – 4 marks
3 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
[4]
© Cambridge International Examinations 2015
.
Mark Scheme
149
Cambridge O Level – May/June 2015
Page 3
2
Syllabus
2210
Paper
12
(i) Either of the three options, resistive, capacitive or infra-red must be chosen
maximum of two marks from chosen technology:
resistive
− uses multiple layers of material …
− … that transmit electric currents
− when the top layer/screen is pushed/touched into the lower/bottom layer …
− … the electric current changes and location of “touch” is found
capacitive
− current sent/flows out from all 4 corners of the screen
− when finger/stylus touches screen, the current changes
− the location of “touch” is calculated
infra-red
− an “invisible” grid on the screen (pattern of infra-red LED beams)
− sensors detect where the screen has been touched through a break in an infrared
beam(s)
− the position where the screen touched is calculated
[2]
(ii) 1 mark for benefit, 1 mark for drawback
Resistive
benefits:
− inexpensive/cheap to manufacture
− can use stylus/finger/gloved finger/pen
drawbacks:
− poor visibility in sunlight
− vulnerable to scratching
− wears through time
− does not allow multi-touch facility
capacitive
benefits:
− good visibility in sunlight
− (very) durable surface
− allows multi-touch facility
drawbacks:
− screen (glass) will shatter/break/crack (on impact)
− cannot use when wearing (standard) gloves
infra-red
benefits:
− good durability
− allows multi-touch facility
− can use stylus/finger/gloved finger/pen
drawbacks:
− expensive to manufacture
− screen (glass) will shatter/break/crack (on impact)
− sensitive to dust/dirt
© Cambridge International Examinations 2015
[2]
.
Mark Scheme
150
Cambridge O Level – May/June 2015
Page 4
3
barcode
reader
microphone
Syllabus
2210
copies paper
documents and
converts the text and
pictures into a
computer-readable form
reads labels containing
parallel dark and light
lines using laser light;
the width of each line
represents a binary
code
Paper
12
voice
recognition
reading
passports
pH sensor
detects changes in
acidity levels; data is
often in analogue form
automatic
stock control
scanner
audio device that allows
audio signals to be
converted into electric
signals which can be
interpreted by a
computer after being
converted into digital
monitor soil in
a greenhouse
Input Device to Description
Description to Application
3/4 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
3/4 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
[6]
© Cambridge International Examinations 2015
4
.
Mark Scheme
151
Cambridge O Level – May/June 2015
Page 5
(a) Any one from:
−
−
−
−
Syllabus
2210
Paper
12
secure sockets layer
encrypts data being transmitted
use of https
use public and private keys
[1]
(b) 1 mark for each number in the correct order, next to the correct stage.
Stage
the encrypted data is then shared securely between the web browser and the
web server
the web browser attempts to connect to a web site which is secured by SSL
Sequence
number
6
(1)
the web server sends the web browser a copy of its SSL certificate
3
the web browser requests the web server to identify itself
2
the web server will then send back some form of acknowledgement to allow the
SSL encrypted session to begin
5
the web browser checks whether the SSL certificate is trustworthy; if it is then
the web browser sends a message back to the web server
4
[5]
© Cambridge International Examinations 2015
5
.
Mark Scheme
152
Cambridge O Level – May/June 2015
Page 6
(a) 1 mark per correctly placed tick
Received byte
Byte transmitted correctly
Syllabus
2210
Paper
12
Byte transmitted incorrectly
11001000
01111100
01101001
[3]
(b) (i) byte number:
7
column number: 6
[2]
(ii) Any two from:
−
−
−
letter “A”(byte 7) transmitted as odd parity (three 1s)
column 6 has odd parity (seven 1s)
intersection of byte 7 and column 6 indicates incorrect bit value
[2]
(c) 190
[1]
(d) Any one from:
−
−
−
2 bits interchanged (e.g. 1 → 0 and 0 → 1) that won’t change parity value
even number of bits/digits are transposed
If there are multiple errors in the same byte/column, that still produce the same parity bit,
the error will not be detected
[1]
© Cambridge International Examinations 2015
.
Mark Scheme
153
Cambridge O Level – May/June 2015
Page 7
6
Syllabus
2210
Paper
12
(a) 1 mark per correct logic gate, correctly connected
G
C
X
L
[5]
(b)
G
C
L
Workspace
X
0
0
0
0
0
0
1
0
0
1
0
1
0
1
1
0
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
0
] 1 mark
] 1 mark
] 1 mark
] 1 mark
[4]
© Cambridge International Examinations 2015
.
Mark Scheme
154
Cambridge O Level – May/June 2015
Page 8
Syllabus
2210
Paper
12
(c) 1 mark for correctly completed truth table
A
B
C
0
0
0
0
1
1
1
0
1
1
1
0
[1]
7 (a)
Maximum 5 marks in total for question part
Description of how street light is controlled: (max 4 marks)
−
−
−
−
−
−
−
sensor sends signal/data to the microprocessor
signal/data converted to digital/using ADC
microprocessor compares value to a stored value
if input value < stored value …
… signal sent from microprocessor to actuator
… and light is switched on/off
whole process continues in an infinite loop
Avoiding frequent on/off switches: (max 2 marks)
−
−
microprocessor continues to keep light on/off for a pre-determined period
after pre-determined period, sensor output is again sampled
[5]
© Cambridge International Examinations 2015
.
Mark Scheme
155
Cambridge O Level – May/June 2015
Page 9
Syllabus
2210
Paper
12
(b) 1 mark for correct sensor, 1 mark for its matching application
(all THREE applications must be different)
sensor
application
infra-red/motion
automatic doors
burglar alarm systems
temperature
chemical process
central heating/air con system
greenhouse environment
oven
sound/acoustic
burglar alarm systems
leak detection system
disco lighting
moisture/humidity
clothes drier
environmental control (greenhouse, air con)
pressure
burglar alarm system
traffic light control
chemical process
carbon dioxide/
oxygen/gas
pollution monitoring in a river
greenhouse environment (growth control)
confined area (e.g. space craft)
Fish tank/Aquarium
magnetic field
mobile phone
anti-lock braking
CD players
[6]
8
1 mark per correct word
Freeware
Shareware
Free software
(Computer) Ethics
Plagiarism
[5]
© Cambridge International Examinations 2015
.
Mark Scheme
156
Cambridge O Level – May/June 2015
Page 10
9
Syllabus
2210
Paper
12
(a) 1 mark per correctly placed tick
statement
interpreter
compiler
creates an executable file that runs directly on the computer
more likely to crash the computer since the machine code
produced runs directly on the processor
easier to debug since each line of code is analysed and
checked before being executed
slow speed of execution of program loops
it is more difficult to modify the code since the executable
code is now in machine code format
[5]
(b) Any one from:
−
−
code is required to be converted into machine code/binary
code needs to be produced that can be understood by the computer
[1]
(c) Any one from:
−
−
−
close to English/native/human language
easier/faster to correct errors/read/write
works on many different machines/operating systems (portable)
[1]
(d) Any one from:
−
−
−
work directly on registers/CPU
more control over what happens in computer
can use machine specific functions
[1]
(e) 1 mark per correct letter, maximum 2 marks
Assembly code:
B
High-level language code: C
Machine code:
A
[2]
© Cambridge International Examinations 2015
.
Mark Scheme
157
Cambridge O Level – May/June 2015
Page 11
Syllabus
2210
Paper
12
10 (a) 1 mark for two correct lines, 2 marks for four correct lines
L (108):
0
1
1
0
1
1
0
0
I (105):
0
1
1
0
1
0
0
1
G (103):
0
1
1
0
0
1
1
1
N (110):
0
1
1
0
1
1
1
0
[2]
(b) 1 mark for each correct binary value
1 mark for each correct hexadecimal value
hexidecimal
L:
1
1
0
1
1
0
0
0
D8
G:
1
1
0
0
1
1
1
0
CE
[4]
© Cambridge International Examinations 2015
.
158
Cambridge International Examinations
Cambridge Ordinary Level
* 4 3 5 7 9 6 3 4 4 8 *
2210/21
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2015
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 11 printed pages and 1 blank page.
DC (SLM) 108497
© UCLES 2015
[Turn over
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159
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release Material
Write and test a program to complete the three tasks.
TASK 1
A data logger records the temperature on the roof of a school twice a day, at midday and midnight.
Input and store the temperatures recorded for a month. You must store the temperatures in two onedimensional arrays, one for the midday temperatures and one for the midnight temperatures. All the
temperatures must be validated on entry and any invalid temperatures rejected. You must decide
your own validation rules. You may assume that there are 30 days in a month.
TASK 2
Calculate the average temperature for midday and the average temperature for midnight. Output
these averages with a suitable message for each one.
TASK 3
Select the day with the highest midday temperature and the day with the lowest midnight temperature.
Then output each of these temperatures, the corresponding day and a suitable message.
Your program must include appropriate prompts for the entry of data. Error messages and other
outputs need to be set out clearly and understandably. All variables, constants and other identifiers
must have meaningful names. Each task must be fully tested.
© UCLES 2015
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160
1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
In Task 1, you had to store the midday temperatures and midnight temperatures in
arrays.
Write suitable declarations for these two arrays.
...........................................................................................................................................
.......................................................................................................................................[2]
(ii)
It has been decided to record the temperatures for one week rather than one month.
Write the new array declarations that you would use.
...........................................................................................................................................
.......................................................................................................................................[1]
(iii)
Declare two other variables that you have used and state what you used each one for.
Variable 1 ...........................................................................................................................
Use .....................................................................................................................................
Variable 2 ...........................................................................................................................
Use .................................................................................................................................[4]
© UCLES 2015
2210/21/M/J/15
[Turn over
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4
161
(b) Write an algorithm to complete Task 2, using either pseudocode, programming statements
or a flowchart. Use temperatures for one week only. You should assume that Task 1 has
already been completed.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
© UCLES 2015
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(c) Give a set of midday temperature data, for a week, that could be used to check your validation
rules for Task 1. Explain why you chose this data set.
Data set .....................................................................................................................................
...................................................................................................................................................
Reason for choice ......................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(d) Explain how you select the day with the highest midday temperature (part of Task 3). You may
include pseudocode or programming statements as part of your explanation.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[6]
© UCLES 2015
2210/21/M/J/15
[Turn over
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163
Section B
2
Read this section of program code that should input 10 positive numbers and then output the
smallest number input.
1
Small = 0
2
Counter = 0
3
REPEAT
4
INPUT Num
5
IF Num < Small THEN Num = Small
6
Counter = Counter + 1
7
PRINT Small
8
UNTIL Counter < 10
There are four errors in this code.
Locate these errors and suggest a corrected piece of code for each error.
1 .......................................................................................................................................................
..........................................................................................................................................................
2 .......................................................................................................................................................
..........................................................................................................................................................
3 .......................................................................................................................................................
..........................................................................................................................................................
4 .......................................................................................................................................................
......................................................................................................................................................[4]
© UCLES 2015
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.
7
164
Question 3 begins on page 8.
© UCLES 2015
2210/21/M/J/15
[Turn over
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8
165
3
The flowchart below inputs the weight of a number of parcels in kilograms. Parcels weighing more
than 25 kilograms are rejected. A value of –1 stops the input.
The following information is output: the total weight of the parcels accepted and number of parcels
rejected.
START
7RWDOĸ
5HMHFWĸ
INPUT
Weight
Is Weight
= –1?
Yes
OUTPUT Total,
Reject
END
No
Is Weight
> 25?
Yes
5HMHFWĸ5HMHFW
No
7RWDOĸ7RWDO:HLJKW
© UCLES 2015
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166
Complete the trace table for the input data:
1.8, 26.0, 7.0, 11.3, 10.0, 2.5, 25.2, 5.0, 19.8, 29.3, –1
Total
Reject
Weight
OUTPUT
[5]
4
Five data types and five data samples are shown below.
Draw a line to link each data type to the correct data sample.
Data type
Data sample
Integer
'a'
Real
2
Char
2.0
String
True
Boolean
"Twelve"
[4]
© UCLES 2015
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67
5
Explain the difference between a variable and a constant in a program.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
......................................................................................................................................................[2]
6
Identify three different loop structures that you can use when writing pseudocode.
1 .......................................................................................................................................................
..........................................................................................................................................................
2 .......................................................................................................................................................
..........................................................................................................................................................
3 .......................................................................................................................................................
......................................................................................................................................................[3]
7
A database, PROPERTY, was set up to show the prices of properties for sale and the features of
each property. Part of the database is shown below.
Brochure
No
Number of
Bedrooms
Number of
Bathrooms
Garden
Garage
Price
in $
Bungalow
B17
7
4
Yes
Yes
750,000
Apartment
A09
2
1
No
No
100,000
House
H10
4
2
Yes
No
450,000
House
H13
3
2
Yes
No
399,000
Apartment
A01
2
2
No
Yes
95,000
Apartment
A16
1
1
No
No
150,000
House
H23
3
1
No
Yes
250,000
House
H46
2
1
Yes
Yes
175,000
Property Type
(a) Give the number of fields that are in each record.
...............................................................................................................................................[1]
© UCLES 2015
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68
(b) State which field you would choose for the primary key.
...................................................................................................................................................
Give a reason for choosing this field.
...................................................................................................................................................
...............................................................................................................................................[2]
(c) State the data type you would choose for each of the following fields.
Garage .....................................................................................................................................
Number of Bedrooms .............................................................................................................
Price in $ ..............................................................................................................................[3]
(d) The query-by-example grid below selects all houses with more than 1 bathroom and more
than 2 bedrooms.
Field: Property Type
Number of
Bedrooms
Number of
Bathrooms
Price in $
Brochure No
Table: PROPERTY
PROPERTY
PROPERTY
PROPERTY
PROPERTY
Sort:
Ascending

Show:
Criteria: = 'House'
>2

>1
or:
Show what would be output.
...................................................................................................................................................
...............................................................................................................................................[2]
(e) Complete the query-by-example grid below to select and show the brochure number, property
type and price of all properties with a garage below $200,000.
Field:
Table:
Sort:
Show:
Criteria:
or:
[4]
© UCLES 2015
2210/21/M/J/15
.
Mark Scheme
169
Cambridge O Level – May/June 2015
Page 2
Syllabus
2210
Paper
21
Section A
1
(a) (i) Many correct answers, they must be meaningful. These are examples only.
– MiddayTemperature[1:30]
or MiddayTemperature[0:29]
or MiddayTemperature[30]
or MiddayTemperature[29]
or MiddayTemperature[]
(1 mark)
– MidnightTemperature[1:30]
or MidnightTemperature[0:29]
or MidnightTemperature[30]
or MidnightTemperature[29]
or MidnightTemperature[]
(1 mark)
(ii) Answers, must match above and the upper bound should have been changed from
30 to 7 or 29 to 6 or no change if not used. These are examples only.
– MiddayTemperature[1:7] MidnightTemperature[1:7]
or MiddayTemperature[7] MidnightTemperature[7]
[2]
[1]
(iii) Any two variables with matching reasons, 1 mark for the variable and 1 mark
for the matching reason. The variables and the matching reasons must relate to
the tasks in the pre-release. There are many possible correct answers these are
examples only.
Variable
– Counter: (Integer)
Reason
– to use as a loop counter when entering the temperature
Variable
Reason
–
–
HighNoon: (Real)
to store the highest midday temperature
© Cambridge International Examinations 2015
[4]
.
Mark Scheme
170
Cambridge O Level – May/June 2015
Page 3
Syllabus
2210
Paper
21
(b) If loop used
– initialisation before loop
– loop
– running total inside loop
– calculation of average outside loop
– output of average with message outside loop
(Max 4 marks)
–
completion of at least 3 of initialisation, running total, calculation of average and
output of average with message for both midday and midnight
(1 mark)
[5]
sample algorithm:
MiddayTotal ← 0; MidnightTotal ← 0
FOR Count ← 1 TO 7
MiddayTotal ← MiddayTotal + MiddayTemperature[Count]
MidnightTotal ← MidnightTotal + MidnightTemperature[Count]
NEXT Count
MiddayAverage ← MiddayTotal/7
MidnightAverage ← MiddayTotal/7
PRINT 'The average midday temperature is ', MiddayAverage
PRINT 'The average midnight temperature is ', MidnightAverage
If loop not used
– total of 7 midday temperatures
– calculation of midday average (Note could be combined as one calculation,
see example below)
– total of 7 midnight temperatures
– calculation of midnight average (Note could be combined as one calculation,
see example below)
– output of both averages with suitable messages
sample algorithm:
MiddayAverage ← (MiddayTemperature[1]+ MiddayTemperature[2]+
MiddayTemperature[3]+ MiddayTemperature[4]+
MiddayTemperature[5]+ MiddayTemperature[6]+
MiddayTemperature[7])/7
MidnightAverage ← (MidnightTemperature[1]+
MidnightTemperature[2]+ MidnightTemperature[3]+ Midnight[4]+
Midnight[5]+ Midnight[6]+ MidnightTemperature[7])/7
PRINT 'The average midday temperature is ', MiddayAverage
PRINT 'The average midnight temperature is ', MidnightAverage
© Cambridge International Examinations 2015
[5]
.
Mark Scheme
171
Cambridge O Level – May/June 2015
Page 4
Syllabus
2210
Paper
21
(c) 1 mark for the data set and 1 mark for the matching reason.
There are many possible correct answers, these are examples only.
Data set
– 30, 29, 28, 31.5, 32.3, 33, 29.7
Reason
– normal data that should be accepted
Data set
Reason
–
–
twenty, 23.99, seventeen, 501, –273, @#@, seventy seven
abnormal data that should be rejected
[2]
(d) Maximum 6 marks in total for question part
Explanation (max 6)
– set variable called HighestMidday to a large minus number
– loop (30 or 7) times to check each midday temperature in turn
– check midday temperature against HighestMidday / midday temperature >
HighestMidday
– …replace value in HighestMidday by midday temperature
– …store array index in MiddayMonthDay/MiddayWeekday
– output HighestMidday outside the loop
– output MiddayMonthDay/MiddayWeekday outside the loop
Sample algorithm (max 4):
HighestMidday ← -999
FOR Count ← 1 TO 7
IF MiddayTemperature [Count] > HighestMidday
THEN HighestMidday ← MiddayTemperature[Count]
MiddayMonthDay/MiddayWeekday ← Count
ENDIF
NEXT Count
PRINT 'The highest midday temperature was ',HighestMidday, ' on
day ', Count
If pseudocode or programming only and no explanation, then maximum 4 marks
© Cambridge International Examinations 2015
[6]
.
Mark Scheme
172
Cambridge O Level – May/June 2015
Page 5
Syllabus
2210
Paper
21
Section B
2
1 mark for each error identified + suggested correction
Line 1 or Small = 0: this should read Small = 999
line 5 or IF…:
this should read IF Num < Small THEN Small = Num
line 8 or UNTIL:
this should read UNTIL Counter = 10 or
UNTIL Counter > = 10 or
UNTIL Counter > 9
line 7 or PRINT…:
PRINT Small should come after the end of the repeat loop
or
line 8 or UNTIL:
this should come before line 7
[4]
3
Total
Reject
0
0
1.8
Weight
1.8
1
26.0
8.8
7.0
20.1
11.3
30.1
10.0
32.6
2.5
2
25.2
37.6
5.0
57.4
19.8
3
(2 marks)
(–1 for each error)
(then follow though)
Output
(1 mark)
29.3
–1
57.4, 3
1 mark)
(1 mark)
(allow follow through)
(from Total and Reject)
[5]
© Cambridge International Examinations 2015
.
Mark Scheme
173
Cambridge O Level – May/June 2015
Page 6
4
Syllabus
2210
Paper
21
1 mark for each correct link, up to maximum of 4 marks
Integer
'a'
Real
2
Char
2.0
String
True
Boolean
'Twelve'
[4]
5
6
7
Any two points from
– a variable is used to store data that can change during the running of a program
– a constant is used to store data that will not be changed during the running of a
program
[2]
–
–
–
[3]
FOR (… TO … NEXT)
REPEAT (… UNTIL)
WHILE (… DO … ENDWHILE)
(a) –
7
[1]
(b) –
–
Brochure No
Uniquely identifies each property
[2]
(c) Garage
Number of Bedrooms
Price in $
(d) 399000
450000
–
–
–
Boolean
Number/Integer/Single
Number/Single/Real/Currency
H13
H10
[3]
[2]
© Cambridge International Examinations 2015
.
Mark Scheme
174
Cambridge O Level – May/June 2015
Page 7
(e)
Syllabus
2210
Field:
Property Type
Garage
Price in $
Brochure No
Table:
PROPERTY
PROPERTY
PROPERTY
PROPERTY
True
< 200000
Paper
21
Sort:
Show:
Criteria:
or:
or
Field:
Property Type
Garage
Price in $
Brochure No
Table:
PROPERTY
PROPERTY
PROPERTY
PROPERTY
Yes
< 200000
Sort:
Show:
Criteria:
or:
or
Field:
Property Type
Garage
Price in $
Brochure No
Table:
PROPERTY
PROPERTY
PROPERTY
PROPERTY
=Yes
< 200000
Sort:
Show:
Criteria:
or:
or
Field:
Property Type
Garage
Price in $
Brochure No
Table:
PROPERTY
PROPERTY
PROPERTY
PROPERTY
=-1
< 200000
(1 mark)
(1 mark)
Sort:
Show:
Criteria:
or:
(1 mark)
(1 mark)
[4]
© Cambridge International Examinations 2015
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175
Cambridge International Examinations
Cambridge Ordinary Level
* 7 0 6 5 7 0 5 1 2 4 *
2210/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2015
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 11 printed pages and 1 blank page.
DC (FD) 110074
© UCLES 2015
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176
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release Material
Write and test a program to complete the three tasks.
TASK 1
A school keeps records of the weights of each pupil. The weight, in kilograms, of each pupil is
recorded on the first day of term. Input and store the weights and names recorded for a class of
30 pupils. You must store the weights in a one-dimensional array and the names in another onedimensional array. All the weights must be validated on entry and any invalid weights rejected. You
must decide your own validation rules. You may assume that the pupils’ names are unique. Output
the names and weights of the pupils in the class.
TASK 2
The weight, in kilograms, of each pupil is recorded again on the last day of term. Calculate and store
the difference in weight for each pupil.
TASK 3
For those pupils who have a difference in weight of more than 2.5 kilograms, output, with a suitable
message, the pupil’s name, the difference in weight and whether this is a rise or a fall.
Your program must include appropriate prompts for the entry of data. Error messages and other
outputs need to be set out clearly and understandably. All variables, constants and other identifiers
must have meaningful names. Each task must be fully tested.
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1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
Declare the array to store the pupils’ names.
.......................................................................................................................................[1]
(ii)
Declare the array to store the pupils’ weights.
.......................................................................................................................................[1]
(iii)
It has been decided to record the weights for the whole school of 600 pupils rather than
one class.
Write suitable new declarations for these two arrays.
...........................................................................................................................................
.......................................................................................................................................[1]
(b) Write an algorithm to complete Task 2, using either pseudocode, programming statements
or a flowchart. Use weights for the whole school. You should assume that Task 1 has already
been completed.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
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(c) (i)
Describe suitable validation rules for Task 1.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
(ii)
Give two pupil weights that you could use to check the validation used in Task 1. Explain
why you chose each weight.
Weight 1 ............................................................................................................................
Reason for choice .............................................................................................................
...........................................................................................................................................
Weight 2 ............................................................................................................................
Reason for choice .............................................................................................................
.......................................................................................................................................[4]
(d) Explain how you select the pupils with a fall in weight of more than 2.5 kilograms (part of
Task 3). You may include pseudocode or programming statements as part of your explanation.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[6]
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Section B
2
Read this section of program code that should input 30 positive numbers and then output the
largest number input.
1
Large = 9999
2
Counter = 0
3
WHILE Counter > 30
4
DO
5
INPUT Num
6
IF Num < Large THEN Large = Num
7
Counter = Counter - 1
8
ENDWHILE
9
PRINT Large
There are four errors in this code.
Locate these errors and suggest a corrected piece of code for each error.
1 .......................................................................................................................................................
..........................................................................................................................................................
2 .......................................................................................................................................................
..........................................................................................................................................................
3 .......................................................................................................................................................
..........................................................................................................................................................
4 .......................................................................................................................................................
......................................................................................................................................................[4]
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3
(a) The flowchart below inputs six single digit numbers. The predefined function MOD gives the
value of the remainder, for example, Y ← 10 MOD 3 gives the value Y = 1
START
INPUT
A, B, C, D, E, F
Total @ A*1 + B*2 + C*3 + D*4 + E*5
Check @ Total MOD 11
Is Check = Yes
F?
No
OUTPUT
'Reject'
END
© UCLES 2015
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OUTPUT
'Accept'
.
7
181
Complete a trace table for each of the two sets of input data.
Set 1
5, 2, 4, 3, 1, 5
Set 2
3, 2, 1, 0, 7, 3
Trace table set 1 5, 2, 4, 3, 1, 5
A
B
C
D
E
F
Total
Check
Output
D
E
F
Total
Check
Output
Trace table set 2 3, 2, 1, 0, 7, 3
A
B
C
[4]
(b) State the purpose of the flowchart in part (a).
...................................................................................................................................................
...............................................................................................................................................[1]
(c) Identify a problem with this flowchart and explain how to correct it.
Problem ....................................................................................................................................
...................................................................................................................................................
Solution .....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
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4
Four programming concepts and four examples of programming code are shown below.
Draw a line to link each programming concept to the correct example of programming code.
Programming
concept
Example of programming code
Counting
Sum = Sum + Value[n]
Repetition
IF Value = 10 THEN PRINT 'X'
Selection
FOR Counter = 1 TO 10
Totalling
Amount = Amount + 1
Sum = Num1 + Num2
[4]
5
(a) Write an algorithm, using pseudocode and a FOR … TO … NEXT loop structure, to input
1000 numbers into an array.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(b) Rewrite your algorithm using another loop structure.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
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183
Question 6 begins on page 10.
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84
6
A database, MARKS, was set up to record the test results for a class of students. Part of the
database is shown below.
Student Name
Class ID
Maths
English
Science
History
Geography
Paul Smith
0017
70
55
65
62
59
Ravi Gupta
0009
29
34
38
41
44
Chin Hwee
0010
43
47
50
45
52
John Jones
0013
37
67
21
28
35
Diana Abur
0001
92
88
95
89
78
Rosanna King
0016
21
13
11
27
15
(a) Give the number of fields that are in each record.
...............................................................................................................................................[1]
(b) State which field you would choose for the primary key.
...................................................................................................................................................
Give a reason for choosing this field.
...................................................................................................................................................
...............................................................................................................................................[2]
(c) The query-by-example grid below selects all students with more than 60 marks in History or
more than 60 marks in Geography.
Field:
Student Name
History
Geography
Table:
MARKS
MARKS
MARKS
Sort:
Show:
Ascending
✓
Criteria:
>60
or:
>60
Show what would be output.
...................................................................................................................................................
...............................................................................................................................................[2]
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85
(d) Complete the query-by-example grid below to select and show the student names only of all
students with less than 40 marks in both Maths and English.
Field:
Table:
Sort:
Show:
Criteria:
or:
[3]
© UCLES 2015
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Page 2
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Mark Scheme
186
Cambridge O Level – May/June 2015
Syllabus
2210
Paper
22
Section A
1
(a) (i) Many correct answers, they must be meaningful. This is an example only.
– PupilName[1:30]
or PupilName[0:29]
or PupilName[30]
or PupilName[29]
or PupilName[]
[1]
(ii) Many correct answers, they must be meaningful. This is an example only.
– StartWeight[1:30]
or StartWeight[0:29]
or StartWeight[30]
or StartWeight[29]
or StartWeight[]
[1]
(iii) Answers, must match (i) and (ii) above and the upper bound should have been changed
from 30 to 600 or 29 to 599 or no change if not used.
– StartWeight[1:600] or StartWeight[600]
– PupilName[1:600] or PupilName[600]
[1]
(b) any four from
– prompt for entry of final weight that includes pupil’s name
– input final weight
– validation check for final weight
– calculation of difference in weight
– ……using the initial weight stored in the array
– store difference in weight
(Max 4 marks)
– loop for 600 pupils
(1 mark)
sample algorithm:
FOR Count 1 TO 600
REPEAT
PRINT 'Please enter weight for ', PupilName[Count]
INPUT FinalWeight
UNTIL FinalWeight < 120 AND FinalWeight > 20
WeightDifference[Count] FinalWeight - StartWeight[Count]
NEXT Count
© Cambridge International Examinations 2015
[5]
.
Mark Scheme
187
Cambridge O Level – May/June 2015
Page 3
Syllabus
2210
Paper
22
(c) (i) any two from
– check that the weights are within a given range
– check that the weights are numeric
– check that the weights are given to one decimal point
– character/type check on name
– length check on name
[2]
(ii) 1 mark for the data and 1 mark for the matching reason.
There are many possible correct answers this is an example only.
Weight 1
– 35.2
Reason
– normal data that should be accepted
Weight 2
Reason
– twenty
– abnormal data that should be rejected
[4]
(d) Maximum 6 marks in total for question part
Explanation (max 6)
– loop 30 or 600 times to check each difference in weight
– check for a difference in weight
– less than -2.5 (final weight – start weight) or greater than 2.5 (start weight – final weight)
– …If so output pupil’s name
– …if so output difference in weight
– …if so output message that it is a fall in weight
Sample algorithm (max 4)
FOR Count 1 TO 30
IF WeightDifference [Count] < -2.5
THEN PRINT PupilName[Count], 'The weight loss was ',
WeightDifference [Count]
ENDIF
NEXT Count
If pseudocode or programming only and no explanation, then maximum 4 marks
© Cambridge International Examinations 2015
[6]
.
Mark Scheme
188
Cambridge O Level – May/June 2015
Page 4
Syllabus
2210
Paper
22
Section B
2
3
1 mark for each error identified + suggested correction
Line 1 or Large =9999:
this should read Large = 0
Line 3 or WHILE:
this should read WHILE Counter < 30
line 6 or IF:
this should read IF Num > Large THEN Large = Num
line 7 or Counter =…: this should read Counter = Counter + 1
[4]
(a)
Trace table set 1
A
B
C
D
E
F
Total
Check
Output
5
2
4
3
1
5
38
5
Accept
-----------------------------------(1 mark)-----------------------------------(1 mark)------
Trace table set 2
A
B
C
D
E
F
Total
Check
Output
3
2
1
0
7
3
45
1
Reject
-----------------------------------(1 mark)-----------------------------------(1 mark)------
[4]
(b) – (modulo 11) check digit calculation
[1]
(c) 1 mark for identifying the problem, 2 marks for the solution
Problem
– doesn’t deal correctly with remainder 10/a check digit of X
Solution
– check Z for X as a final digit
– have a special case where check = 10
– accept where Check = 10 and F = X
[3]
© Cambridge International Examinations 2015
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Mark Scheme
189
Cambridge O Level – May/June 2015
Page 5
4
Syllabus
2210
Paper
22
1 mark for each correct line, two lines from one box not allowed
Counting
Sum = Sum + Value[n]
Repetition
IF Value = 10 THEN PRINT
'X'
Selection
FOR Counter = 1 TO 10
Amount = Amount + 1
Totalling
Sum = Num1 + Num2
[4]
5
(a) 1 mark for FOR … TO … NEXT 1 mark for INPUT
FOR Count 1 TO 1000
INPUT A[Count]
NEXT (Count)
[2]
(b) 4 marks
– initialisation
– start of loop
– update loop counter
– end of loop
Example1
Count 1
REPEAT
INPUT A[Count]
Count Count + 1
UNTIL Count > 1000
Example2
Count 0
WHILE Count < 1000
DO
Count Count + 1
INPUT A[Count]
ENDWHILE
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
[4]
© Cambridge International Examinations 2015
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Mark Scheme
190
Cambridge O Level – May/June 2015
Page 6
6
(a) – 7
Syllabus
2210
Paper
22
[1]
(b) – Class ID
– Uniquely identifies each student
[2]
(c) Diana Abur, Paul Smith
– both names
– ……. correct order
[2]
(d)
Field: Student Name
Table: MARKS
Maths
English
MARKS
MARKS
Sort:
Show:
Criteria:
<40
<40
or:
(1 mark)
(1 mark)
© Cambridge International Examinations 2015
(1 mark)
[3]
.
191
Cambridge International Examinations
Cambridge Ordinary Level
*8805434291*
2210/12
COMPUTER SCIENCE
Paper 1 Theory
October/November 2015
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 12 printed pages.
© UCLES 2015
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192
1
There are a number of security risks associated with using the Internet.
Name three of these risks. For each, state why it is a risk and describe how the risk can be
minimised.
Security risk 1 ...................................................................................................................................
Why it is a risk ..................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
How to minimise the risk ..................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Security risk 2 ...................................................................................................................................
Why it is a risk ...................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
How to minimise the risk ..................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Security risk 3 ...................................................................................................................................
Why it is a risk ..................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
How to minimise the risk ..................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[9]
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2
Seven computer terms and seven descriptions are shown below.
Draw a line to link each computer term to its most appropriate description.
Computer term
Description
Interface
Reduction of file size by permanently removing
some redundant information from the file
Interrupt
File compression format designed to make
photo files smaller in size for storage and for
transmission
JPEG
File compression system for music which does
not noticeably affect the quality of the sound
Lossless
compression
Hardware component that allows the user to
communicate with a computer or operating
system
Lossy
compression
The file is reduced in size for transmission and
storage; it is then put back together again later
producing a file identical to the original
MIDI
MP3 format
Signal sent to a processor which may cause
a break in execution of the current routine,
according to priorities
Standard adopted by the electronic music
industry for controlling devices such as
synthesisers and sound cards
[6]
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3
The flowchart on the opposite page shows what happens when the barcode on a product is
scanned at the checkout in a supermarket. The barcodes are used in an automatic stock control
system.
Several of the statements in the flowchart are missing.
Using item number only from the list below, complete the flowchart.
Item
number
© UCLES 2015
Statement
1
Add flag to product record to indicate re-order made
2
Any more barcodes to scan?
3
Has the scanned barcode been found in the file?
4
Has the re-order flag already been added to the product record?
5
Is number of product in stock <= re-order level?
6
Number of product in stock is reduced by 1
7
Output an error message
8
Automatically send out order for new product
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START
Barcode on product
is scanned
END
No
Yes
Barcode is looked up
in stock database
No
Yes
Yes
Any more
barcodes
to scan?
No
No
Yes
Yes
END
No
[4]
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4
(a) (i)
Convert the following two hexadecimal numbers into binary:
FA7
D3E
FA7
D3E
[4]
(ii)
Now perform the AND (logic) operation on each corresponding pair of binary bits in the
two numbers from part (i).
[2]
(iii)
Convert your answer in part (ii) into hexadecimal.
...........................................................................................................................................
...........................................................................................................................................
[2]
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(b) (i)
The following code shows HTML ‘tag’ pairs on either side of the text stating the colour
that each creates.
<font color “ # F F 0 0 0 0 “ > RED </font>
<font color “ # 0 0 F F 0 0 “ > GREEN </font>
<font color “ # 0 0 0 0 F F “ > BLUE </font>
<font color “ #
<font color “ #
<font color “ #
X
Y
Z
“ > YELLOW </font>
“ > MAGENTA </font>
“ > CYAN </font>
Yellow is a combination of red and green, magenta a combination of red and blue and
cyan a combination of green and blue.
State what 6-digit hexadecimal values should replace X, Y and Z in the above code.
X ........................................................................................................................................
Y ........................................................................................................................................
Z ........................................................................................................................................
[3]
(ii)
Describe how other colours, such as a darker shade of blue, are created.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
[2]
(c) 1A – 16 – C5 – 22 – FF – FF is an example of a MAC address.
(i)
Identify what the first six and last six hexadecimal digits represent.
First six digits ....................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
Last six digits .....................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
[2]
(ii)
State why MAC addresses are used.
...........................................................................................................................................
...........................................................................................................................................
[1]
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5
A security system uses sensors, a camera and a microprocessor to capture images of each person
entering a large shopping mall.
(a) Describe how the sensors, camera and microprocessor interact to identify certain people
entering the mall.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[5]
(b) Each image taken requires 1 MB of storage. If the camera captures an image every 5 seconds
over a 24 hour period, how much storage is required?
Give your answer in gigabytes and show all your working.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
(c) The shopping mall has over 100 cameras. At the end of each day all these cameras send
their images, captured over the last 24 hours, to a central computer.
Explain why the mall uses dedicated fibre optic cable rather than transmitting the data over
the local broadband network.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
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6
(a) Explain what is meant by HTML.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [3]
(b) HTML uses both structure and presentation.
Describe what is meant by the two terms.
Structure ....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Presentation ..............................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
(c) Explain the function of a web browser.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
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00
7
(a) Check digits are used to ensure the accuracy of input data.
A 7-digit code number has an extra digit on the right, called the check digit.
Digit position
1
2
3
4
5
6
7
8
Digit
–
–
–
–
–
–
–
–
The check digit is calculated as follows:
•
each digit in the number is multiplied by its digit position
•
the seven results are then added together
•
this total is divided by 11
•
the remainder gives the check digit (if the remainder = 10, the check digit is X)
(i)
Calculate the check digit for the following code number. Show all your working.
4
2
4
1
5
0
8
…
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
Check digit ........................................................................................................................
[2]
(ii)
An operator has just keyed in the following code number:
3
2
4
0
0
4
5
X
Has the operator correctly keyed in the code number?
...........................................................................................................................................
Give a reason for your answer.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
[3]
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01
(b) When data are transmitted from one device to another, a parity check is often carried out on
each byte of data. The parity bit is often the leftmost bit in the byte.
(i)
If a system uses even parity, give the parity bit for each of the following bytes:
parity bit
1
1
0
0
1
1
0
0
0
0
0
0
0
1
parity bit
[2]
(ii)
A parity check can often detect corruption of a byte.
Describe a situation in which it cannot detect corruption of a byte.
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[1]
8
The steps to print a document using a laser printer are shown in the table below.
Put each step in the correct order. The first step has been done for you.
Step
Order
As the printing drum rotates, a laser scans across it; this removes the
positive charge in certain areas
The printing drum is coated in positively-charged toner; this then sticks to the
negatively-charged parts of the printing drum
The paper goes through a fuser which melts the toner so it fixes permanently
to the paper
The printer driver ensures that the data is in a format that the laser printer
can understand
1
A negatively-charged sheet of paper is then rolled over the printing drum
Data is then sent to the laser printer and stored temporarily in the printer
buffer
The toner on the printing drum is now transferred to the paper to reproduce
the required text and images
The printing drum is given a positive charge
Negatively-charged areas are then produced on the printing drum; these
match exactly with the text and images to be printed
[8]
© UCLES 2015
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02
9
A remote-controlled model car contains RAM, ROM and a solid state drive. The car receives
radio signals from its remote control. It can only receive radio signals of a certain frequency. The
manufacturer sets this frequency and the owner cannot change it. The owner of the model car can
input their own sequence of movements from an interface underneath the car.
(a) Describe the purpose of each of the three types of memory supplied with the car.
RAM ..........................................................................................................................................
...................................................................................................................................................
ROM .........................................................................................................................................
...................................................................................................................................................
Solid state drive ........................................................................................................................
...................................................................................................................................................
[3]
(b) The owner needs to be able to enter their own sequence of movements for the model car.
Name a suitable input device.
Input device ..............................................................................................................................
...................................................................................................................................................
Give a reason for your choice of device.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
(c) Explain why the model car uses a solid state drive rather than another type of secondary
storage.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2015
2210/12/O/N/15
Page 2
1
.
Mark Scheme
203
Cambridge O Level – October/November 2015
Syllabus
2210
Paper
12
1 mark for each risk + 1 mark for corresponding reason why it is a risk and 1 mark for method
of minimisation
Risk:
Reason:
Minimised:
Risk:
Reason:
Minimised:
hacking
illegal/unauthorised access to data
deletion/amendment of data
use of passwords/user ids
use of firewalls
encrypt data/encryption
virus
can corrupt/delete data
cause computer to crash/run slow
can fill up hard drive with data
use of /run anti-virus (software)
do not download software or data from unknown sources
Risk:
Reason:
Minimised:
spyware/key logging (software)
can read key presses/files/monitors on a user’s computer
use of/run anti-spyware (software)
use data entry methods such as drop-down boxes to minimise risk
Risk:
Reason:
phishing
link/attachments takes user to fake/bogus website
website obtains personal/financial data
do not open/click emails/attachments from unknown sources
some firewalls can detect fake/bogus websites
Minimised:
Risk:
Reason:
Minimised:
pharming
redirects user to fake/bogus website
redirection obtains personal/financial data
only trust secure websites, e.g. look for https
check the URL matches the intended site
Risk:
Reason:
Minimised:
credit card fraud/identity theft
loss of money due to misuse of card/stealing data
set passwords
encrypt data/encryption
Risk:
Reason:
Minimised:
cracking
illegal/unauthorised access to data
setting strong passwords
encrypt data/encryption
There may be other valid answers given that are outside the provided mark scheme.
[9]
© Cambridge International Examinations 2015
.
Mark Scheme
204
Cambridge O Level – October/November 2015
Page 3
2
Interface
Interrupt
JPEG
Lossless
compression
Lossy
compression
MIDI
MP3 format
Syllabus
2210
Paper
12
Reduction of file size by permanently
removing certain, redundant information
from the file
File compression format designed to make
photo files smaller in size for storage and
for transmission
File compression system for music which
does not noticeably affect the quality of the
sound
Hardware component that allows the user
to communicate with a computer or
operating system
The file is reduced in size for transmission
and storage; it is then put back together
again later producing a file identical to the
original
Signal sent to a processor which may cause
a break in execution of the current routine,
according to priorities
Standard adopted by the electronic music
industry for controlling devices such as
synthesisers and sound cards
[6]
© Cambridge International Examinations 2015
.
Mark Scheme
205
Cambridge O Level – October/November 2015
Page 4
3
START
Syllabus
2210
Paper
12
[4]
barcode on product is
scanned
END
No
barcode is looked up
in stock database
Yes
2
1 mark
No
3
7
Yes
1 mark
6
Yes
No
5
1 mark
any more
barcodes
to scan?
No
Yes
Yes
4
END
No
1/8
1 mark
8/1
[4]
© Cambridge International Examinations 2015
.
Mark Scheme
206
Cambridge O Level – October/November 2015
Page 5
4
(a)
Syllabus
2210
Paper
12
(i) For each hex number, 2 marks if all correct, 1 mark for 2 correct conversions
F A 7:
1
1
1
1
1
0
1
0
0
1
1
1
D 3 E:
1
1
0
1
0
0
1
1
1
1
1
0
[4]
(ii) 2 marks if all correct, 1 mark for 2 correct conversions – Follow through
1
1
0
1
0
0
1
0
0
1
1
0
[2]
(iii) 2 marks if all correct, 1 mark for 2 correct conversions – Follow through
D26
(b) (i) (X)
FF FF 00
(Y)
FF 00 FF
(Z)
00 FF FF
(ii) –
–
[3]
hex values between 0 to F are combined together to create a hex code
different combinations in hex codes will create different shades/tones/colours
(c) (i) First six digits:
Last six digits:
[2]
[2]
manufacturer code/manufacturer ID
serial number/serial ID of device/product
(ii) Allows all devices to be uniquely identified
© Cambridge International Examinations 2015
[2]
[1]
Page 6
5
.
Mark Scheme
207
Cambridge O Level – October/November 2015
Syllabus
2210
Paper
12
(a) Any five from:
– naming a suitable sensor, e.g infra-red, pressure, motion sensors, send signal/data to
microprocessor
– signal/data is converted to digital (using an ADC)
– microprocessor instructs/send signals to camera to capture image/video
– captured image/video data sent to microprocessor
either
– microprocessor compares the image/video with stored images/video…
– … if person detected = stored image …
– …alert given to signal a person has been identified
or
– microprocessor compares the biometric data from an image/video with stored biometric
data for images/video …
– … if biometric data matched = stored data …
– … alert given to signal a person has been identified
– Continual/repeated process
[5]
(b) 1 mark for correct calculation, 1 mark for correct answer
– number of photos = 12 × 60 × 24 = 17 280
– memory requirement = 17 280/1024 = 16.9 (16.875)
– (17 280/1000 = 17.28/17.3 is acceptable)
[2]
(c) Any two from:
– (data transmission) is faster
– more secure/safer (because it is a dedicated line)
– (fibre optic transmission) is more reliable
[2]
© Cambridge International Examinations 2015
Page 7
6
.
Mark Scheme
208
Cambridge O Level – October/November 2015
Syllabus
2210
(a) Any three from:
– hypertext mark-up language
– used to create/develop/author webpages
– translated by a browser to display webpages
– uses (opening and closing) tags to display/format content
Paper
12
[3]
(b) Structure:
– instructs how the layout of the content is displayed
7
Presentation:
– instructs how the content will be formatted e.g. colour/style/CSS
[2]
(c) Any three from:
– displays web page
– interprets/translates the HTML document
– interprets/translates embedded scripting, for example JavaScript
– provides functions, such as bookmarks and history
– identifies protocols, such as https, SSL
[3]
(a) (i) 1 mark for correct check digit and 1 mark for showing the calculation
(4 × 1) + (2 × 2) + (4 × 3) + (1 × 4) + (5 × 5) + (0 × 6) + (8 × 7)
= 4 + 4 + 12 + 4 + 25 + 0 + 56 = 105
105/11 = 9 remainder 6
check digit is: 6
[2]
(ii) 1 mark
– No/incorrect check digit
2 marks
– Total is 78
– 78/11 …
– … gives 7 remainder 1
– check digit should be 1
© Cambridge International Examinations 2015
[3]
.
Mark Scheme
209
Cambridge O Level – October/November 2015
Page 8
(b) (i) 1 mark for each correct parity bit
Syllabus
2210
Paper
12
parity bit
0
1
1
0
0
1
1
0
0
0
0
0
0
0
1
parity bit
1
[2]
(ii) Any one from:
– an even number of digits are changed
– a transposition error(s) has occurred
8
[1]
1 mark for each step in correct order. (NOTE: Marks can be awarded for a correct sequence.)
Steps in the printing process
Step order
As the printing drum rotates, a laser scans across it; this removes the
positive charge in certain areas
4
The printing drum is coated in positively-charged toner; this then sticks to
the negatively-charged parts of the printing drum
6
The paper goes through a fuser which melts the toner so it fixes
permanently to the paper
9
The printer driver ensures that the data is in a format that the laser printer
can understand
(1)
A negatively-charged sheet of paper is then rolled over the printing drum
7
Data is then sent to the laser printer and stored temporarily in the printer
buffer
2
The toner on the printing drum is now transferred to the paper to
reproduce the required text and images
8
The printing drum is given a positive charge
3
Negatively-charged areas are then produced on the printing drum; these
match exactly with the text and images to be printed
5
[8]
© Cambridge International Examinations 2015
Page 9
9
.
Mark Scheme
210
Cambridge O Level – October/November 2015
Syllabus
2210
Paper
12
(a) RAM
– contains instructions/program/data currently in use
ROM
any one from:
– contains the start-up/bootstrap program
– contains/stores the setting for frequency (can’t be changed)
Solid state drive
– stores the instructions/program/data (to operate the car)
[3]
(b) 1 mark for device and 1 mark for corresponding reason
Device:
– touch screen
– key pad (NOT keyboard)
Reason:
– easy to use interface
– limited number of options
– small space/space is limited
– other devices such as mouse, keyboard, trackerball, … not suitable
(c) Any two from:
– A solid state drive has no moving parts
– A solid state drive has faster random access
– A solid state drive has a quick start up/shut down time (reduced latency)
– A solid state drive is very small
– A solid state drive is very light
– A solid state drive consumes very little power
– A solid state drive does not generate a lot of heat (therefore safer in this application)
© Cambridge International Examinations 2015
[2]
[2]
.
211
Cambridge International Examinations
Cambridge Ordinary Level
* 7 0 6 3 0 8 3 5 0 6 *
2210/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
October/November 2015
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 11 printed pages and 1 blank page.
DC (LK/CGW) 113106
© UCLES 2015
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2
212
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release Material
Write and test a program to complete the three tasks.
A new born baby is kept in a cot in a hospital; the temperature of the baby is monitored every
10 minutes. The temperature of the baby is recorded in degrees Celsius to one decimal place and
must be within the range 36.0°C to 37.5°C.
TASK 1
To simulate the monitoring required, write a routine that allows entry of the baby’s temperature in
degrees Celsius. The routine should check whether the temperature is within the acceptable range,
too high or too low and output a suitable message in each case.
TASK 2
Write another routine that stores the temperatures taken over a three hour period in an array. This
routine should output the highest and lowest temperatures and calculate the difference between
these temperatures.
TASK 3
For a baby who has a temperature difference of more than one degree Celsius, and/or has been
outside the acceptable range more than twice in the three hour period, output a suitable message
giving a summary of the problem.
Your program must include appropriate prompts for the entry of data. Error messages and other
outputs need to be set out clearly and understandably. All variables, constants and other identifiers
must have meaningful names. Each task must be fully tested.
© UCLES 2015
2210/22/O/N/15
.
3
213
1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
When you performed the tasks, you used variables.
Write suitable declarations for two of these.
State what you used each one for.
Variable 1 ..........................................................................................................................
Use ....................................................................................................................................
Variable 2 ..........................................................................................................................
Use ................................................................................................................................[4]
(ii)
When you performed the tasks, you may have used constants.
Write suitable declarations for two of these.
State what you used each one for.
Constant 1 .........................................................................................................................
Use ....................................................................................................................................
...........................................................................................................................................
Constant 2 .........................................................................................................................
Use ....................................................................................................................................
.......................................................................................................................................[4]
© UCLES 2015
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214
(b) Write an algorithm to complete Task 1, using either pseudocode, programming statements
or a flowchart.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
© UCLES 2015
2210/22/O/N/15
.
5
215
(c) (i)
Explain how you completed Task 3. You can include pseudocode or programming
statements as part of your explanation. You should assume that Task 2 has been
completed.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[5]
(ii)
Comment on the efficiency of your design for Task 3.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
© UCLES 2015
2210/22/O/N/15
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216
Section B
2
Read this section of program code that should input 50 numbers and then output the average.
1
Total = 0
2
For Counter = 1 TO 50
3
INPUT Num
4
Total = Total + 1
5
Counter = Counter + 1
6
Average = Total/Counter
7
NEXT Counter
8
PRINT Average
There are four errors in this code.
Locate these errors and suggest code corrections to remove each error.
1 .......................................................................................................................................................
..........................................................................................................................................................
2 .......................................................................................................................................................
..........................................................................................................................................................
3 .......................................................................................................................................................
..........................................................................................................................................................
4 .......................................................................................................................................................
......................................................................................................................................................[4]
© UCLES 2015
2210/22/O/N/15
.
7
217
Question 3 begins on page 8.
© UCLES 2015
2210/22/O/N/15
[Turn over
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8
218
3
(a) The flowchart inputs an integer. The predefined function DIV gives the integer result of the
10 DIV 3 gives the value Y = 3. The predefined function MOD gives the
division, e.g. Y
10 MOD 3 gives the value Y = 1.
value of the remainder, e.g. Y
START
Posn @ 1
New @ 0
INPUT X
T1 @ X DIV 2
T2 @ X MOD 2
New @New+T2 * Posn
Posn @Posn * 10
X @T1
Yes
is T1
>= 2?
No
New @New+T1 * Posn
OUTPUT New
END
© UCLES 2015
2210/22/O/N/15
.
9
219
Complete a trace table for each of the two input values 5 and 12.
Trace table for input value 5
X
Posn
New
T1
T2
OUTPUT
T1
T2
OUTPUT
Trace table for input value 12
X
Posn
New
[6]
(b) State the purpose of the flowchart in part (a).
...............................................................................................................................................[1]
© UCLES 2015
2210/22/O/N/15
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20
4
A routine checks the weight of melons to be sold in a supermarket. Melons weighing under
0.5 kilograms are rejected and melons weighing over 2 kilograms are also rejected.
Give an example of each type of test data for this routine.
Normal .............................................................................................................................................
Extreme ............................................................................................................................................
Abnormal ......................................................................................................................................[3]
5
Identify two different conditional statements that you can use when writing pseudocode.
1 .......................................................................................................................................................
2 ...................................................................................................................................................[2]
6
A picture gallery owner has decided to set up a database to keep information about the pictures
he has for sale. The database table, PICTURE, will contain the following fields:
Title; Artist; Description; Catalogue Number; Size (area in square centimetres); Price; Arrived (date
picture arrived at gallery); Sold (whether picture is already sold)
(a) (i)
State what data type you would choose for each field.
Title ...................................................................................................................................
Artist ..................................................................................................................................
Description ........................................................................................................................
Catalogue Number ............................................................................................................
Size ...................................................................................................................................
Price ..................................................................................................................................
Arrived ...............................................................................................................................
Sold ...............................................................................................................................[4]
(ii)
State which field you would choose for the primary key.
.......................................................................................................................................[1]
© UCLES 2015
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21
(b) Give a validation check that you can perform on each of these fields. Each validation check
must be different.
Catalogue Number ....................................................................................................................
Size ...........................................................................................................................................
Price .........................................................................................................................................
Arrived ..................................................................................................................................[4]
(c) Complete the query-by-example grid below to select and show the Catalogue Number, Title
and Price of all unsold pictures by the artist ‘Twister’.
Field:
Table:
Sort:
Show:
Criteria:
or:
[5]
© UCLES 2015
2210/22/O/N/15
Page 2
.
Mark Scheme
222
Cambridge O Level – October/November 2015
Syllabus
2210
Paper
22
Section A
1
(a) (i) Any two variables with matching uses, one mark for the variable name and one mark for
the matching use. The variables and the matching uses must relate to the tasks on the
exam paper. There are many possible correct answers these are examples only.
Variable 1 – Counter(: INTEGER)
Use
– to use as a loop counter when entering the temperatures
Variable 2 – BabyTemperature(: REAL)
Use
– to store the baby’s temperature
[4]
(ii) Any two constants with matching uses, one mark for the constant (name and value) and
one mark for the matching use. The constants and the matching uses must relate to the
tasks on the exam paper. There are several possible correct answers these are
examples only.
Constant 1 – MinBabyTemperature = 36.0
Use
– to keep the lowest acceptable baby temperature
Constant 2 – MaxBabyTemperature = 37.5
Use
– to keep the highest acceptable baby temperature
[4]
(b) Any five from
– prompt for baby’s temperature
– input baby’s temperature
– test for > 37.5
– … then output suitable message if this is the case
– test for < 36.0
– … then output suitable message if this is the case
– output suitable message if temperature between those values
Sample algorithm:
PRINT 'Please enter temperature of baby '
INPUT BabyTemperature
IF BabyTemperature > MaxBabyTemperature or 37.5
THEN Print 'Temperature too high'
ELSE
IF BabyTemperature < MinBabyTemperature or 36.0
THEN Print 'Temperature too low'
ELSE Print 'Temperature OK'
ENDIF
ENDIF
© Cambridge International Examinations 2015
[5]
.
Mark Scheme
223
Cambridge O Level – October/November 2015
Page 3
Syllabus
2210
Paper
22
(c) (i) Explanation
General marks award as seen
Give one mark for a mention of any one of the 4 checks below
If a mark is given for a check then mark the corresponding action taken
Maximum of five marks overall
General
– check all recorded temperatures (loop 18 times)
– update counter for those out of range
– output suitable message if counter >= 2
1
2
3
4
check if temperature range <= 1 and highest recorded not out of range and
lowest recorded not out of range
– ... exit
check if temperature range > 1...
– … output suitable message e.g. "Temperature range greater than one degree"
check if highest recorded temperature out of range…
– … output a suitable message if at least two recorded temperatures out of range
e.g. "Temperature too high on more than one occasion"
check if lowest recorded temperature out of range…
– … output a suitable message if at least two recorded temperatures out of range
e.g. "Temperature too low on more than one occasion"
[5]
(ii) Any two from
– only checks necessary conditions
– uses results from task 2
– checks for normal values first
© Cambridge International Examinations 2015
[2]
.
Mark Scheme
224
Cambridge O Level – October/November 2015
Page 4
Syllabus
2210
Paper
22
Section B
2
One mark for each error identified + suggested correction
line 4 or (Total =) Total + 1: this should read (Total =) Total + Num
line 5 or Counter = Counter + 1: delete this line
line 6 or (Average = )Total / Counter: swap lines 6 and 7
line 6 or (Average = )Total / Counter : this should read (Average =) Total / 50
[4]
3
(a)
Number 1 Trace table
X
Posn
New
5
1
0
10
100
2
T1
T2
1
2
1
1
1
0
Output
101
101
(1 mark)
(1 mark)
(1 mark)
Number 2 Trace table
X
Posn
New
T1
T2
12
1
0
10
0
6
0
6
100
0
3
0
3
1000
100
1
1
Output
1100
1100
(1 mark)
(1 mark)
(1 mark)
(b) Converts a (denary) number to binary
© Cambridge International Examinations 2015
[6]
[1]
.
Mark Scheme
225
Cambridge O Level – October/November 2015
Page 5
4
5
6
Syllabus
2210
Paper
22
There are many possible correct answers this is an example only.
Normal
e.g. 1.7
Extreme
0.5 or 2.0 only
Abnormal
e.g. one
[3]
– IF (… THEN … ELSE … ENDIF)
– CASE (… OF … OTHERWISE … ENDCASE)
[2]
(a) (i) One mark for every two correct types
Title
– text
Artist
– text
Description
– text/memo
Catalogue Number – text/(auto)number
Size
– number
Price
– currency/number
Arrived
– date
Sold
– “yes/no”/text/Boolean
0, 1 no marks
2, 3 one mark
4, 5 two marks
6, 7 three marks
8 four marks
[4]
(ii) Catalogue Number
[1]
(b) One mark for each correct different check
Catalogue Number Format check/Presence Check/Check Digit/Length check/uniqueness
check
Size
Type check/Presence Check/Range Check
Price
Type check/Presence Check/Range Check
Arrived
Type check/Presence Check/Range Check/Format check/Select from
calendar length check
[4]
(c)
Field:
Catalogue
Number
Title
Price
Artist
Sold
Table:
PICTURE
PICTURE
PICTURE
PICTURE
PICTURE
='Twister'
False
Sort:
Show:
Criteria:
or:
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
[5]
© Cambridge International Examinations 2015
.
226
Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
* 3 3 0 4 3 8 2 2 2 0 *
0478/12
COMPUTER SCIENCE
Paper 1 Theory
May/June 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 14 printed pages and 2 blank pages.
DC (NH/JG) 118886/3
© UCLES 2016
[Turn over
.
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227
1
2
Complete the following by writing either compiler, interpreter or assembler in the spaces
provided.
.....................................................................
– translates source code into object code.
......................................................................
– translates low-level language into machine code.
......................................................................
– stops the execution of a program as soon as it
encounters an error.
[3]
Motion sensors are used in a security system to detect intruders.
Name three other sensors that could be used in the following applications.
Give a different type of sensor for each application.
Application
Sensor
controlling street lights
monitoring a river for pollution
controlling traffic lights
[3]
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3
(a) Convert the following hexadecimal number into 12-bit binary:
4AF
[3]
(b) The 2016 Olympic Games will be held in Rio de Janeiro. A timer that counts down to the
opening of the Games is shown on a microprocessor-controlled display.
The number of hours, minutes and seconds until the Games open are held in three 8-bit
registers.
The present register values are:
0
1
1
0
1
0
0
1
105 hours
0
0
1
0
0
0
0
0
32 minutes
0
0
0
1
0
1
0
0
20 seconds
The timer will count down in seconds.
(i)
Show the values in each 8-bit register 30 seconds after the time shown above:
hours
minutes
seconds
[3]
(ii)
Write the hexadecimal value of the minutes register from part (b)(i).
.......................................................................................................................................[1]
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4
Nigel wants to send a large text file electronically to Mashuda.
(a) Describe how the size of the text file can be reduced.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
(b) This file will be transmitted to Mashuda as an email attachment. Mashuda then stores it on
her computer.
Explain how checksums can be used to verify that the file has not been corrupted during
transmission or data storage.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
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5
Six descriptions and six devices are shown below.
Draw a line to link each description to the correct device.
Description
Device
Allows a user to write on a surface
using a pen; text and drawings are
then captured electronically and
stored for later use.
Digital Light Projector
Converts sound into an electrical
signal/voltage.
Inkjet printer
Uses thermal bubble and piezoelectric
technology to produce a hard copy.
Interactive whiteboard
Uses a bright white light source and
micro mirrors (on a chip) to produce
an image to be shone onto a wall or
screen.
Laser printer
Converts a hard copy document into
an electronic form to be stored as a
file on a computer.
Microphone
Uses negatively charged images on a
rotating drum and positively charged
toner to output a hard copy.
Scanner (2D)
[5]
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6
(a) Three descriptions of data transmission are given below.
Tick (✓) the appropriate box in each table to show the:
•
•
type of transmission
method of transmission
Description 1:
Type
Data is transmitted several bits at
a time down several wires in both
directions simultaneously.
Tick
(✓)
Method
simplex
serial
half-duplex
parallel
Tick
(✓)
full-duplex
Description 2:
Type
Data is transmitted in one direction
only, one bit at a time, down a
single wire.
Tick
(✓)
Method
simplex
serial
half-duplex
parallel
Tick
(✓)
full-duplex
Description 3:
Type
Data is transmitted one bit at a
time down a single wire; the data
is transmitted in both directions
but not at the same time.
Tick
(✓)
Method
simplex
serial
half-duplex
parallel
Tick
(✓)
full-duplex
[6]
(b) Give two reasons why serial transmission, rather than parallel transmission, is used to
connect devices to a computer.
1 ................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
[2]
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(a)
$
;
%
&
Complete the truth table for this logic circuit.
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Working space
X
[4]
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(b) Draw a logic circuit corresponding to the following logic statement:
X = 1 if ( ( A is 1 OR B is 1 ) AND ( A is 1 AND B is 1 ) ) OR ( C is NOT 1 )
$
%
;
&
[5]
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(c) Re-draw the following logic circuit using NAND gates only.
$
;
%
&
Logic circuit re-drawn:
$
%
;
&
[4]
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8
(a) Five statements and three types of software are shown below.
Draw lines to connect each statement with the correct type of software.
Statement
Type of software
Users have the freedom to pass on
the software to friends and family as
they wish.
Free software
Users can download this software free
of charge, but they cannot modify the
source code in any way.
Users are allowed to try out the
software for a trial period only before
being charged.
Freeware
Users can study the software source
code and modify it, where necessary,
to meet their own needs, without
breaking copyright laws.
Shareware
Users can obtain a free trial version
of the software, but this often does
not contain all the features of the full
version.
[3]
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(b) Describe three ethical issues that should be considered when using computers.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
(c) Security of data is very important.
Three security issues are viruses, pharming and spyware.
Explain what is meant by each issue.
Viruses: .....................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Pharming: .................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Spyware: ...................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[6]
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(d) Describe three tasks carried out by a firewall.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
9
In the following barcode, each binary number is made up of seven bars.
Each bar is black or grey.
A black bar is interpreted as a “1” and a grey bar is interpreted as a “0”.
(a) Write the binary numbers that would be produced from this barcode:
%LQDU\QXPEHU$ %LQDU\QXPEHU%
Binary number A:
Binary number B:
[2]
(b) This barcode system uses odd parity.
Write the parity bit for each of the binary numbers in part (a):
Parity bit
Binary number A:
Binary number B:
[2]
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10 There are six descriptions in the table below.
Complete the table below by writing the correct storage device or media in the box next to each
description.
Description
Storage device or media
Non-volatile memory that can only be read from and not
written to.
Optical storage media that allows very high storage capacity
by using blue/violet laser technology.
Volatile memory that stores data, programs and the parts of
the operating system that are currently in use.
Optical storage media that uses a single spiral track and uses
dual layer technology, allowing high data storage capacity.
Device that stores data by controlling the movement of
electrons within a microchip; there are no moving parts.
Optical storage media that uses concentric tracks allowing
writing and reading to take place at the same time.
[6]
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11 Describe the use of structure and presentation in a HTML document.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
......................................................................................................................................................[4]
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
COMPUTER SCIENCE
0478/12
May/June 2016
Paper 1
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2016 series for most Cambridge IGCSE®,
Cambridge International A and AS Level components and some Cambridge O Level components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 10 printed pages.
© UCLES 2016
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Mark Scheme
241
Cambridge IGCSE – May/June 2016
Page 2
1
compiler
Syllabus
0478
Paper
12
assembler
interpreter
[3]
2
Application
Sensor
controlling street lights
Light
monitoring a river for pollution
Gas, pH, temperature, light
controlling traffic lights
pressure, magnetic field,
NOTE: The same sensor cannot be given twice
3
[3]
(a) 1 mark for each nibble
0100 1010 1111
(b) (i) 0 1 1 0 1 0 0 1
00011111
00110010
[3]
105 hours
31 minutes
50 seconds
1 mark
1 mark
1 mark
(ii) 1F
[3]
[1]
© Cambridge International Examinations 2016
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Mark Scheme
242
Cambridge IGCSE – May/June 2016
Syllabus
0478
Paper
12
(a) Any three from:
– The file can be compressed
– The compression that is used is lossless (not lossy)
– use of a compression algorithm
– repeated words can be indexed
– repeated word sections (e.g. “OU”) can be replaced by a numerical value
– reference to zip files
– save file as a pdf/convert to pdf
[3]
(b) Any four from:
– the checksum for the bytes is calculated
– this value is then transmitted with the block of data
– at the receiving end, the checksum is re-calculated from the block of data received
– the calculated value is then compared to the checksum transmitted
– if they are the same value, then the data was transmitted without any error
– if the values are different, then an error has been found
– if the values are different, then a request is sent for the data to be re-transmitted
[4]
© Cambridge International Examinations 2016
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Mark Scheme
243
Cambridge IGCSE – May/June 2016
5
Syllabus
0478
Description
Device
Allows a user to write on a
surface using a pen; text and
drawings are then captured
electronically and stored for
later use.
Digital Light Projector
Converts sound into an
electrical signal/voltage.
Uses thermal bubble and
piezoelectric technology to
produce a hard copy.
Paper
12
Inkjet printer
Interactive whiteboard
Uses a bright white light source
and micro mirrors (on a chip) to
produce an image to be shone
onto a wall or screen.
Converts a hard copy document
into an electronic form to be
stored as a file on a computer.
Uses negatively charged
images on a rotating drum and
positively charged toner to
output a hard copy.
5/6 matches – 5 marks
4 matches – 4 marks
3 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
© Cambridge International Examinations 2016
Laser printer
Microphone
Scanner (2D)
[5]
Page 5
6
.
Mark Scheme
244
Cambridge IGCSE – May/June 2016
(a)
Type
Tick
()
Method
simplex
serial
half-duplex
parallel
full-duplex
Type
simplex
Syllabus
0478
Paper
12
Tick
()
Tick
()
half-duplex
Method
serial
Tick
()
parallel
full-duplex
Type
Tick
()
simplex
half-duplex
Method
serial
Tick
()
parallel
full-duplex
[6]
(b) Any two from:
– single wire means there is less chance of interference/data corruption
– single wire reduces costs
– more reliable over greater distances
– bits will still be synchronised after transmission
© Cambridge International Examinations 2016
[2]
.
Mark Scheme
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Cambridge IGCSE – May/June 2016
Page 6
7
(a)
Working space
Syllabus
0478
A
B
C
0
0
0
0
0
0
1
1
0
1
0
0
0
1
1
1
1
0
0
0
1
0
1
1
1
1
0
1
1
1
1
0
4 marks for 8 correct X bits
3 marks for 6 correct X bits
2 marks for 4 correct X bits
1 mark for 2 correct X bits
© Cambridge International Examinations 2016
Paper
12
X
[4]
.
Mark Scheme
246
Cambridge IGCSE – May/June 2016
Page 7
Syllabus
0478
Paper
12
(b) 1 mark for each correct gate with correct source of input
A
X
B
C
[5]
(c) Each dotted area is 1 mark
A
X
B
C
[4]
© Cambridge International Examinations 2016
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Mark Scheme
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Cambridge IGCSE – May/June 2016
Syllabus
0478
Paper
12
(a) 1 mark for correct lines from each type of software
NOTE: all statements that are correct must be connected to the correct type of
software for the mark to be awarded
Statement
Type of software
Users have the freedom to
pass on the software to
friends and family as they
wish.
Free software
Users can download this
software free of charge, but
they cannot modify the
source code in any way.
Users are allowed to try out
the software for a trial period
only before being charged.
Freeware
Users can study the software
source code and modify it,
where necessary, to meet
their own needs, without
breaking copyright laws.
Shareware
Users can obtain a free trial
version of the software, but
this often does not contain all
the features of the full
version.
[3]
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Cambridge IGCSE – May/June 2016
Syllabus
0478
Paper
12
(b) Any three from:
– That we should follow Copyright laws/intellectual property rights/work should not be
stolen/plagiarised
– That we should follow Data Protection laws
– That we should not create or distribute malware//description of malware
– That we should not hack/crack other computers//description of hacking
– That we should protect our own computers against malware/hacking
– That we should consider privacy issues (when using social networking)
– That we consider anonymity issues (when using social networking)
– That we should consider environmental impacts when using computers
– Loss/creation of jobs from use of computers/robotics
– We should follow codes of practice (for creation of code e.g. ACM/IEEE)
[3]
(c) 2 marks for each term described
Viruses:
– program/software/file that replicates (copies) itself
– intends to delete or corrupt files//fill up hard disk space
Pharming:
– malicious code stored on a computer/web server
– redirects user to fake website to steal user data
Spyware:
– monitors and relays user activity e.g. key presses//key logging software
– user activity/key presses can be analysed to find sensitive data e.g. passwords
[6]
(d) Any three from:
– examines/monitors traffic to and from a user’s computer and a network/Internet
– checks whether incoming and outgoing traffic meets a given set of criteria/rules
– firewall blocks/filters traffic that doesn’t meet the criteria/rules
– logs all incoming and outgoing traffic
– can prevent viruses or hackers gaining access
– blocks/filters access to specified IP addresses/websites
– warns users of attempts by software (in their computer) trying to access external data
sources (e.g. updating of software) etc. // warns of attempted unauthorised access to
the system
[3]
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(a)
Syllabus
0478
Binary number A:
1
1
1
0
0
1
0
Binary number B:
1
0
0
1
1
1
0
Paper
12
[2]
(b)
Parity Bit
Binary number A
1
Binary number B
1
[2]
10 1 mark for each correct storage device
ROM (not EPROM/PROM)
Blu-ray disc
RAM
DVD/ DVD-R(+R)/ DVD-RW(+RW)/ DVD-ROM (not CD or DVD-RAM)
SSD/example of a USB storage device
DVD-RAM
[6]
11 1 mark for each correct point
– Presentation is used to format colour/style
– Structure is used to create layout
– In a HTML document structure and presentation are often kept separate
– By keeping the presentation separate it is easier to update colour/font
– Presentation is often stored in a file called a CSS …
– … the CSS in then linked to the HTML document to implement the presentation requirements
– (Mark-up) tags are used to define the structure of the document …
– … presentation and formatting can also be included within the tags
[4]
© Cambridge International Examinations 2016
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
* 0 7 3 3 6 7 4 3 7 5 *
0478/13
COMPUTER SCIENCE
Paper 1 Theory
May/June 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 13 printed pages and 3 blank pages.
DC (ST/CGW) 126906
© UCLES 2016
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251
1
Some software can be described as free, freeware or shareware.
Tick (✓) the appropriate boxes in the table below to show which features apply to these three
types of software.
Software feature
Free
Freeware
Shareware
Software source code can be freely accessed and
modified as required
All the features of the full version of the software
are not made available; the full version needs to be
purchased first
The original software is subject to all copyright laws
It is possible to distribute modified versions or
copies of the software to friends and family
[3]
2
Hexadecimal codes are used in MAC addresses.
(a) State what is meant by the term MAC.
...............................................................................................................................................[1]
(b) Explain what the hexadecimal code in a MAC address represents.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
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3
(a) Five sensors and five applications are shown below.
Draw a line to link each sensor to its most appropriate application.
Sensor
Application
Light
sensor
Monitor the pollution levels in a river
Moisture
sensor
Control the switching off and on of
street lights
Gas
sensor
Detect intruders breaking into a
building
pH
sensor
Monitor the amount of water left in
clothes in a dryer
Pressure
sensor
Monitor acidity levels in the soil in a
greenhouse
[4]
(b) Automatic doors in a building are controlled by the use of infrared sensors and a
microprocessor.
Describe how the sensors and the microprocessor are used to automatically open a door as
a person approaches.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
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253
4
(a) Nikita wishes to print out some documents and connects her printer to the computer using
one of the USB ports.
(i)
Identify what type of data transmission is being used.
.......................................................................................................................................[1]
(ii)
Give three reasons for using a USB port.
1 .......................................................................................................................................
...........................................................................................................................................
2 .......................................................................................................................................
...........................................................................................................................................
3 .......................................................................................................................................
...........................................................................................................................................
[3]
(iii)
The printer runs out of paper while it is printing the documents. A signal is sent to the
processor to request that the problem is dealt with.
Name this type of signal.
.......................................................................................................................................[1]
(b) State one suitable application for each printer below. A different application must be given for
each printer.
Inkjet printer ..............................................................................................................................
...................................................................................................................................................
3D printer ..................................................................................................................................
...................................................................................................................................................
[2]
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(c) Name another type of printer and describe one way in which it is different from the printers
named in part (b).
Give an application for this printer.
Type of printer ...........................................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Application ................................................................................................................................
...................................................................................................................................................
[3]
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5
A computer-controlled machine produces plastic sheets. The thickness of each sheet must be
within a certain tolerance. The sheets are kept below 50 °C as they move over rollers at 10 metres
per second.
Three parameters need to be monitored all the time.
Parameter
D
S
T
Description
Binary
value
Conditions
1
thickness of sheet in tolerance
0
thickness of sheet out of tolerance
1
roller speed = 10 metres/second
0
roller speed <> 10 metres/second
1
temperature < 50 °C
0
temperature >= 50 °C
sheet thickness
roller speed
temperature
An alarm, X, will sound if:
thickness is in tolerance AND (roller speed <> 10 metres/second OR temperature >= 50 °C)
OR
roller speed = 10 metres/second AND temperature >= 50 °C
(a) Draw a logic circuit to represent the above monitoring system.
D
S
X
T
[6]
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(b) Complete the truth table for the monitoring system.
D
S
T
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Working Space
X
[4]
6
Secure socket layer (SSL) is used in the security of information on Internet websites.
(a) State how it is possible for a user to know that a website is secure by looking at the web
address.
...................................................................................................................................................
...............................................................................................................................................[1]
(b) Describe three of the stages a web browser goes through to detect whether a website is
secure.
1 ...............................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ...............................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3 ...............................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
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7
Each seat on a flight is uniquely identified on an LCD above the seat. For example, seat 035C is
shown as:
The first three characters are digits that represent the row.
The fourth character is the seat position in that row. This is a single letter, A to F, that is stored as a
hexadecimal value.
Each of the four display characters can be stored in a 4-bit register. For example, 0 and C would
be represented as:
0:
C:
8
4
2
1
0
1
0
1
0
0
0
0
(a) Show how the 4-bit registers would store the remaining two characters, 3 and 5.
3
5
[2]
(b) Identify which seat is stored in the following 4-bit registers.
0
0
0
1
1
0
0
1
0
1
0
0
1
1
1
0
[2]
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258
8
A bank offers an online service to its customers. The bank has developed a “SafeToUse” system
that asks each customer to enter four randomly chosen characters from their password each time
they log in.
The customer selects these four characters from drop-down boxes. For example:
Please select the
2nd character
5th character
6th character
8th character
(a) (i)
Explain why it is more secure to use drop-down boxes rather than entering characters
using a keyboard.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
(ii)
Give a reason why the system asks for four characters chosen at random.
...........................................................................................................................................
.......................................................................................................................................[1]
(b) Biometrics is an additional form of security.
Give two examples of biometrics.
1 ...............................................................................................................................................
2 ...............................................................................................................................................
[2]
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9
Check digits are used to ensure the accuracy of entered data.
A 7-digit number has an extra digit on the right, called the check digit.
digit position:
1
2
3
4
5
6
7
8
digit:
–
–
–
–
–
–
–
–
check digit
The check digit is calculated as follows:
•
•
•
•
each digit in the number is multiplied by its digit position
the seven results are then added together
this total is divided by 11
the remainder gives the check digit (if the remainder = 10, the check digit is X)
(a) Calculate the check digit for the following number. Show all your working.
4
2
4
1
5
0
8
…
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Check digit ................................................................................................................................
[2]
(b) An operator has just keyed in the following number:
3
2
4
0
0
4
5
X
Circle below correct if the check digit is correct OR incorrect if the check digit is incorrect.
correct
incorrect
Explain your answer.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
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60
10 Six security issues and six descriptions are shown below.
Draw a line to link each security issue to its correct description.
Security issue
Description
Pharming
illegal access to a computer system
without the owner’s consent or
knowledge
Phishing
software that gathers information by
monitoring key presses on a user’s
keyboard; the data is sent back to the
originator of the software
Viruses
malicious code installed on the hard
drive of a user’s computer or on a web
server; this code will re-direct the user
to a fake website without the user’s
knowledge
Hacking
creator of code sends out a
legitimate-looking email in the hope
of gathering personal and financial
information from the recipient; it
requires the user to click on the link in
the email or attachment
Spyware
a message given to a web browser by
a web server; it is stored in a text file;
the message is then sent back to the
server each time the browser requests
a page from the server
Cookies
program or code that replicates itself;
designed to amend, delete or copy
data or files on a user’s computer;
often causes the computer to crash or
run slowly
[5]
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61
11 (a) Four examples of optical storage media are:
•
•
•
•
DVD-RW
DVD-RAM
CD-ROM
Blu-ray disc
The table below shows four features of optical storage media.
Tick (✓) the appropriate boxes in the table to indicate which of the features apply to each
example of optical storage media.
Single track
Many
concentric
tracks
Blue laser
used to read/
write data
Red laser
used to read/
write data
DVD-RW
DVD-RAM
CD-ROM
Blu-ray disc
[4]
(b) Solid state drives (SSD) are replacing hard disc drives (HDD) in some computers.
(i)
Give three reasons why this is happening.
1 .......................................................................................................................................
...........................................................................................................................................
2 .......................................................................................................................................
...........................................................................................................................................
3 .......................................................................................................................................
...........................................................................................................................................
[3]
(ii)
Explain why many web servers still use hard disc drive (HDD) technology.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
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62
12 (a) Name the following type of barcode:
...............................................................................................................................................[1]
(b) The barcode in part (a) contains the denary value
2640
Convert this value to hexadecimal.
...................................................................................................................................................
...................................................................................................................................................
Write the value as a 12-bit binary number.
[4]
(c) An airport uses the type of barcode shown in part (a) to advertise local places of interest.
Describe how a visitor landing at the airport could use these barcodes to help plan their visit.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
COMPUTER SCIENCE
0478/13
May/June 2016
Paper 1
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2016 series for most Cambridge IGCSE®,
Cambridge International A and AS Level components and some Cambridge O Level components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 10 printed pages.
© UCLES 2016
[Turn over
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Mark Scheme
264
Cambridge IGCSE – May/June 2016
Page 2
1 mark for each correct column
Software feature
Free
Software source code can be freely accessed
and modified as required
Syllabus
0478
Freeware
Shareware
All the features of the full version of the software
are not made available; the full version needs to
be purchased first
The original software is subject to all of the
copyright laws
It is possible to distribute modified versions or
copies of the software to friends and family
Paper
13
(1 mark)
(1 mark)
(1 mark)
[3]
2
(a) media access control
[1]
(b) Any three from:
–
–
–
–
–
hardware/physical address
unique address/number associated (with network card in) a device/computer
usually 48/64 bits (12/16 hex digits)
first 6/8 digits = manufacturer code/ID of device (NIC)
last 6/8 digits = serial number of device (NIC)
© Cambridge International Examinations 2016
[3]
.
Mark Scheme
265
Cambridge IGCSE – May/June 2016
Page 3
3
(a)
Light
sensor
Syllabus
0478
Paper
13
Monitoring the pollution levels in a river
Moisture
sensor
Control the switching off and on of
street lighting
Gas
sensor
Detection of intruders breaking into a
building
pH
sensor
Monitor the amount of water left in
clothes in a drier
Pressure
sensor
Monitor acidity levels in the soil in a
greenhouse
4/5 matches – 4 marks
3 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
[4]
(b) Any four from:
–
–
–
–
–
–
sensor(s) sends signal/data to microprocessor
signal/data converted to digital (using an ADC)
microprocessor compares signal/data with pre-set/stored value
if sensor(s) signal/data indicates the presence of a person / the door needs to be opened
/ a match is found / door is closed …
… microprocessor sends a signal to an actuator …
… to operate/drive a motor to open the door
[4]
© Cambridge International Examinations 2016
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Mark Scheme
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Cambridge IGCSE – May/June 2016
Page 4
(a) (i) serial
Syllabus
0478
Paper
13
[1]
(ii) Any three from:
– automatically detects the hardware/installs drivers
– plug only goes in one way/can’t connect incorrectly
– supports different data transmission speeds/a range of data transmission speeds
– has become the industry standard/universally used
– backwards compatible (with earlier versions of USB ports)
[3]
(iii) interrupt
[1]
(b) 1 mark each use of printer, max 1 mark per printer.
inkjet printer
– (small quantities of) documents
– photographs
3D printer
– (physical) prototype (from CAD)
– (physical) model (from a blueprint)
[2]
(c) 1 mark for naming printer + 1 mark for description + 1 mark for application
Laser printer
–
–
–
–
–
–
–
uses toner/powder ink
uses (positive and negative) charged drums // rotating drum
uses static charge
no moving head
faster at printing
high volume output/high speed
producing flyers/leaflets/magazines
This is an example, other types of printers can be credited.
© Cambridge International Examinations 2016
[3]
.
Mark Scheme
267
Cambridge IGCSE – May/June 2016
Page 5
5
Syllabus
0478
Paper
13
(a) 1 mark for each correct gate, with correct source of input(s)
[6]
(b)
D
S
T
Working Space
0
0
0
0
0
0
1
0
0
1
0
1
0
1
1
0
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
0
4 marks for 8 correct X bits
3 marks for 6 correct X bits
2 marks for 4 correct X bits
1 mark for 2 correct X bits
© Cambridge International Examinations 2016
X
[4]
.
Mark Scheme
268
Cambridge IGCSE – May/June 2016
Page 6
6
Syllabus
0478
Paper
13
(a) Any one from:
–
–
protocol ends in “s”
use of https
[1]
(b) Any three from:
–
–
–
–
–
–
7
requests web server to identify itself/view the (SSL) certificate
receives a copy of the (SSL) certificate, sent from the webserver
checks if SSL certificate is authentic/trustworthy
sends signal back to webserver that the certificate is authentic/trustworthy
starts to transmit data once connection is established as secure
if website is not secure browser will display an open padlock/warning message
[3]
(a) 1 mark for each correct binary value
3
0
0
1
1
5
0
1
0
1
[2]
(b)
0
0
0
1
1
1
0
0
1
9
0
1
0
0
4
1
1
1
0
E
1 mark
1 mark
[2]
© Cambridge International Examinations 2016
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Mark Scheme
269
Cambridge IGCSE – May/June 2016
Page 7
(a) (i) Any two from:
–
–
–
–
–
Syllabus
0478
Paper
13
to protect against key logging software/spyware
can stop key presses being recorded
can stop key presses being relayed
drop down boxes cannot be recorded as key presses
drop down boxes can be placed in different location on the screen each time
(to overcome screen capture issues)
[2]
(ii) Any one from:
–
–
–
–
hacker never finds all characters on the first hack
makes it more difficult for hackers to find the order of the characters
hacker needs to hack the system several times to gain the whole password
shoulder surfing will not give person full password
[1]
(b) Any two from:
–
–
–
–
9
fingerprint scanner
face recognition software
retina scanner/iris scanner
voice recognition software
[2]
(a) 1 mark for correct check digit and 1 mark for showing the calculation
(4 × 1) + (2 × 2) + (4 × 3) + (1 × 4) + (5 × 5) + (0 × 6) + (8 × 7)
= 4 + 4 + 12 + 4 + 25 + 0 + 56 = 105
1 mark for any correct
line of working
105/11 = 9 remainder 6
check digit is: 6
[2]
(b) incorrect check digit
[1]
–
–
–
check digit should be 1
(3*1) + (2*2) + (4*3) + (0*4) + (0*5) + (4*6) + (5*7) // 3 + 4 + 12 + 0 + 0 + 24 + 35 //
Total = 78
78/11 gives 7 remainder 1
© Cambridge International Examinations 2016
[2]
.
Mark Scheme
270
Cambridge IGCSE – May/June 2016
Page 8
10
Syllabus
0478
Paper
13
illegal access to a computer system
without the owner’s consent or
knowledge
Pharming
software that gathers information by
monitoring key presses on a user’s
keyboard; the information is relayed back
to the originator of the software
Phishing
Viruses
malicious code installed on the hard drive
of a user’s computer or on a web server;
this code will re-direct the user to a fake
website without the user’s knowledge
Hacking
creator of code sends out a legitimatelooking email in the hope of gathering
personal and financial information from
the recipient; it requires the user to click
on the link in the email or attachment
a message given to a web browser by a
web server; it is stored in a text file; the
message is then sent back to the server
each time the browser requests a page
from the server
Spyware
program or code that replicates itself
designed to amend, delete or copy data
or files on a user’s computer; often
causes the computer to crash or run
slowly
Cookies
5/6 matches – 5 marks
4 matches – 4 marks
3 matches – 3 marks
2 matches – 2 marks
1 match – 1 mark
© Cambridge International Examinations 2016
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Cambridge IGCSE – May/June 2016
Page 9
11 (a) 1 mark for each correct row
Single track
Many
concentric
tracks
DVD-RAM
CD-ROM
Blu-ray disc
Paper
13
Red laser
Blue laser
used to read/ used to read/
write data
write data
DVD-RW
Syllabus
0478
1 mark
1 mark
1 mark
1 mark
[4]
(b) (i) Any three from:
–
–
–
–
–
–
–
–
don’t need to “get up to speed” to work properly/no latency
lower/less power consumption/more energy efficient
run cooler
run quieter
data access is faster
occupies less physical space/more compact
lighter, so more suitable for a portable computer/laptop
no moving parts so more reliable/durable in a portable computer/laptop
[3]
(ii) Any two from:
–
–
–
–
HDD is cheaper for larger amounts of storage space
HDD has greater longevity for read/write functions
Expensive to change the technology // HDD are trusted technology
No requirement for the increased speed of SSD
© Cambridge International Examinations 2016
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272
Cambridge IGCSE – May/June 2016
Page 10
12 (a) QR (quick response) Code
(b) –
Syllabus
0478
Paper
13
[1]
A 5 0 (1 mark)
1
0
1
1 mark
0
0
1
0
1
0
0
1 mark
0
0
1 mark
[4]
(c) Any three from:
-
visitor scans the QR code with (the camera on) the mobile device
App is used to read/interpret the QR code
links to a website/opens a document …
… to access local tourist information
can store the QR code to refer to again for the information
© Cambridge International Examinations 2016
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
0478/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2016
PRE-RELEASE MATERIAL
No Additional Materials are required.
* 7 5 2 8 5 0 0 7 1 8 *
This material should be given to the relevant teachers and candidates as soon as it has been received
at the Centre.
READ THESE INSTRUCTIONS FIRST
Candidates should use this material in preparation for the examination. Candidates should attempt the
practical programming tasks using their chosen high-level, procedural programming language.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 2 printed pages.
DC (LK) 106761/3
© UCLES 2016
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274
In preparation for the examination candidates should attempt the following practical tasks by writing
and testing a program(s).
The manager of a building materials delivery service needs a program to check the contents and weight
of sacks to ensure that correct orders are made up for delivery. A price for the order will be calculated.
Write and test a program for the manager.
•
Your program must include appropriate prompts for the entry of data.
•
Error messages and other output need to be set out clearly.
•
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Check the contents and weight of a single sack
Each sack must obey the following rules to be accepted:
•
•
•
contain cement, gravel or sand, with a letter on the side for easy identification
o C - cement
o G - gravel
o S - sand
sand or gravel must weigh over 49.9 and under 50.1 kilograms
cement must weigh over 24.9 and under 25.1 kilograms
Input and store the weight and contents for one sack. The contents must be checked and an incorrect
sack rejected. The weight must be validated on entry and an overweight or underweight sack rejected.
Output the contents and weight of an accepted sack. If a sack is rejected, output the reason(s).
TASK 2 – Check a customer’s order for delivery
Input and store the number of sacks of each type required for the order. Use TASK 1 to check the
contents and weight of each sack. Ensure that the delivery contains the correct number and type of
sacks for the order.
Output the total weight of the order.
Output the number of sacks rejected from the order.
TASK 3 – Calculate the price for a customer’s order
Extend TASK 2 to calculate a price for an order. Prices for the sacks are as follows:
•
•
regular price for each sack
o cement, $3
o gravel, $2
o sand, $2
discount price for a special pack containing 1 sack of cement, 2 sacks of sand and 2 sacks of
gravel, $10
Calculate and output the regular price for the order. Check how many special packs are in the order. If
a discount price applies then output the new price for the order and the amount saved.
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable
effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will
be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2016
0478/22/M/J/16
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
* 9 6 2 0 1 2 8 5 4 9 *
0478/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 11 printed pages and 1 blank page.
DC (LK/SW) 106762/3
© UCLES 2016
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276
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release Material
The manager of a building materials delivery service needs a program to check the contents and
weight of sacks to ensure that correct orders are made up for delivery. A price for the order will be
calculated.
Write and test a program for the manager.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Check the contents and weight of a single sack
Each sack must obey the following rules to be accepted:
•
•
•
contain cement, gravel or sand, with a letter on the side for easy identification
o C - cement
o G - gravel
o S - sand
sand or gravel must weigh over 49.9 and under 50.1 kilograms
cement must weigh over 24.9 and under 25.1 kilograms
Input and store the weight and contents for one sack. The contents must be checked and an incorrect
sack rejected. The weight must be validated on entry and an overweight or underweight sack rejected.
Output the contents and weight of an accepted sack. If a sack is rejected, output the reason(s).
TASK 2 – Check a customer’s order for delivery
Input and store the number of sacks of each type required for the order. Use TASK 1 to check the
contents and weight of each sack. Ensure that the delivery contains the correct number and type of
sacks for the order.
Output the total weight of the order.
Output the number of sacks rejected from the order.
TASK 3 – Calculate the price for a customer’s order
Extend TASK 2 to calculate a price for an order. Prices for the sacks are as follows:
•
•
regular price for each sack
o cement, $3
o gravel, $2
o sand, $2
discount price for a special pack containing 1 sack of cement, 2 sacks of sand and 2 sacks of
gravel, $10
Calculate and output the regular price for the order. Check how many special packs are in the order. If
a discount price applies then output the new price for the order and the amount saved.
© UCLES 2016
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1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
For three of the variables that you have used in Task 2, state the name, type and its use.
Variable 1 name ................................................................................................................
Type ...................................................................................................................................
Use ....................................................................................................................................
Variable 2 name ................................................................................................................
Type ...................................................................................................................................
Use ....................................................................................................................................
Variable 3 name ................................................................................................................
Type ...................................................................................................................................
Use ................................................................................................................................[3]
(ii)
State three constants that you could have used for Task 1. Give the value that would be
assigned to each one.
Constant 1 name ...............................................................................................................
Value 1 ..............................................................................................................................
Constant 2 name ...............................................................................................................
Value 2 ..............................................................................................................................
Constant 3 name ...............................................................................................................
Value 3 ..........................................................................................................................[3]
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(b) Write an algorithm to complete Task 2, using either pseudocode, programming statements
or a flowchart. You can assume that the weight and contents have already been checked and
accepted in Task 1. You do not need to output the number of sacks rejected.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
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(c) (i)
Give two different data values that could be used to check your validation rules for sand
in Task 1. Explain why you chose each value.
Sand data value 1 .............................................................................................................
Reason for choice .............................................................................................................
...........................................................................................................................................
Sand data value 2 .............................................................................................................
Reason for choice .............................................................................................................
.......................................................................................................................................[2]
(ii)
Give two different data values that could be used to check your validation rules for
cement in Task 1. Explain why you chose each value.
Cement data value 1 ..........................................................................................................
Reason for choice ..............................................................................................................
...........................................................................................................................................
Cement data value 2 ..........................................................................................................
Reason for choice ..............................................................................................................
.......................................................................................................................................[2]
(d) Explain how your program calculates the price for an order (Task 3). You may include
programming statements as part of your explanation.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
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Section B
2
Read this section of program code that inputs 10 positive numbers and then outputs the total.
1
Total = 0
2
Counter = 0
3
REPEAT
4
INPUT Num
5
Total = Total + Num
6
PRINT Total
7
Counter = Counter + 1
8
UNTIL Counter = 10
This code works, but it is inefficient.
(i)
Suggest three improvements that could be made.
1 .................................................................................................................................................
...................................................................................................................................................
2 .................................................................................................................................................
...................................................................................................................................................
3 .................................................................................................................................................
...............................................................................................................................................[3]
(ii) Rewrite the program code with your improvements.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
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3
The flowchart below calculates the number of tins of paint required to paint walls. The flowchart
inputs the height and width of a wall in metres, the number of doors and the number of windows.
A value of –1 for the height stops the input.
START
Area
Tins
0
0
INPUT Height,
Width, Doors,
Windows
Is
Height
= –1?
Yes
Tins
INT(Area/10 + 0.5)
No
OUTPUT Tins
Area
Area + Height * Width
– Doors * 1.5 – Windows
END
Complete the trace table for the input data:
3, 5, 1, 0, 3, 7, 0, 0, 3, 5, 0, 3, 3, 7, 1, 1, –1, 0, 0, 0
Area
Tins
Height
Width
Doors
Windows
[4]
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4
Four statement types and four examples are shown below.
Draw a line to connect each statement type to the correct example.
Statement type
Example
Assignment
FOR X
1 TO 10
Iteration
READ X
Input
PRINT X
Output
X
Y + Z
[3]
5
A programmer writes a program to store a patient’s temperature every hour for a day.
State the data structure that would be most suitable to use and give the reason for your choice.
Data structure ...................................................................................................................................
Reason ..............................................................................................................................................
......................................................................................................................................................[2]
6
Identify two different selection statements that you can use when writing pseudocode.
1 ........................................................................................................................................................
..........................................................................................................................................................
2 ........................................................................................................................................................
......................................................................................................................................................[2]
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83
7
A database, SOFASELECT, was set up to show the prices of suites, sofas and chairs for sale from
an online furniture warehouse. Part of the database is shown below.
Brochure
Number
Number
of Seats
Number
of Pieces
Material
Colour
Sofa
SF17
2
1
Leather
Red
950
Sofa
SF19
3
1
Vinyl
Black
1,000
Suite
SU10
4
3
Velvet
Green
1,500
Suite
SU23
5
3
Leather
Brown
950
Recliner chair
RC01
1
1
Leather
Cream
600
Chair
CH16
1
1
Vinyl
Red
250
Recliner sofa
RS23
4
1
Leather
Cream
Chair
CH10
1
1
Velvet
Red
Description
Price in $
1,200
175
(a) How many fields are in each record?
...............................................................................................................................................[1]
(b) State which field you would choose for the primary key.
...................................................................................................................................................
Give a reason for choosing this field.
...................................................................................................................................................
...............................................................................................................................................[2]
(c) State the data type you would choose for each of the following fields.
Number of Seats .....................................................................................................................
Price in $ ..............................................................................................................................[2]
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(d) The query-by-example grid below selects all the furniture in cream leather.
Field: Description
Material
Colour
Price in $
Brochure Number
Table: SOFASELECT
SOFASELECT
SOFASELECT
SOFASELECT
SOFASELECT
Sort:
Descending

Show:
Criteria:

= ‘Leather’

= ‘Cream’
or:
Show the output from the query-by-example.
...................................................................................................................................................
...............................................................................................................................................[3]
(e) Complete the query-by-example grid below to select and show the brochure number, material,
colour and price of all the furniture with 3 or more seats.
Field:
Table:
Sort:
Show:
Criteria:
or:
[5]
© UCLES 2016
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285
Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
COMPUTER SCIENCE
0478/22
May/June 2016
Paper 2
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2016 series for most Cambridge IGCSE®,
Cambridge International A and AS Level components and some Cambridge O Level components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 6 printed pages.
© UCLES 2016
[Turn over
.
Mark Scheme
286
Cambridge IGCSE – May/June 2016
Page 2
Syllabus
0478
Paper
22
Section A
1
(a) (i) Many correct answers, they must be meaningful. This is an example only.
– NumSacks, integer, number of sacks
– SacksAccepted, integer, number of sacks accepted
– TotalWeight, real, total weight of all sacks
[3]
(ii) Any three from
–
–
–
–
TopWeight, 50.1
BottomWeight 49.9
TopWeightCement 25.1
BottomWeightCement 24.9
[3]
(b) Any five from:
– initialise total weight of order
– input number of sacks for each type outside loop(s)
– loop for order completion
– input weight
inside loop(s)
– add weight of accepted sack to total weight
– output total weight
outside all loop(s)
– appropriate prompts for input number of sacks for each type and input weight
Max 5 marks
Sample Answer 1
INPUT 'Number of sand sacks ordered ' num_sand_ordered
INPUT 'Number of cement sacks ordered ' num_cement_ordered
INPUT 'Number of gravel sacks ordered ' num_gravel_ordered
total_weight ← 0
FOR Counter ← 1 TO num_sand_ordered
INPUT 'weight of sack of sand ' sack_weight
total_weight ← total_weight + sack_weight
NEXT Counter
FOR Counter ← 1 TO num_cement_ordered
INPUT 'weight of sack of cement ' sack_weight
total_weight ← total_weight + sack_weight
NEXT Counter
FOR Counter ← 1 TO num_gravel_ordered
INPUT 'weight of sack of gravel' sack_weight
total_weight ← total_weight + sack_weight
NEXT Counter
Print 'Total weight of sacks is ' total_weight
© Cambridge International Examinations 2016
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Mark Scheme
287
Cambridge IGCSE – May/June 2016
Page 3
Syllabus
0478
Paper
22
Sample Answer 2
INPUT 'Number of sand sacks ordered ' num_sand_ordered
INPUT 'Number of cement sacks ordered ' num_cement_ordered
INPUT 'Number of gravel sacks ordered ' num_gravel_ordered
total_sacks_ordered ← num_sand_ordered + num_cement_ordered +
num_gravel_ordered
total_weight ← 0
FOR Counter ← 1 TO total_sacks_ordered
INPUT 'weight of sack ' sack_weight
total_weight ← total_weight + sack_weight
NEXT Counter
Print 'Total weight of sacks is ' total_weight
(c) (i) 1 mark for value reason, all values and reasons must be different. There are many
possible correct answers these are examples only.
Data value
Reason – normal data sand should be accepted
Data value
Reason – boundary data sand should be rejected
49.95
50.1
[2]
(ii)
Data value
Reason – normal data cement should be accepted
25
Data value
26.7
Reason – abnormal data cement that should be rejected
[2]
(d) Maximum 5 marks in total, maximum 3 marks if only programming statements used
Description (may include reference to program statements)
–
use of prices for calculation of regular price either numbers, variables or constants (sand
and gravel 2, cement 3)
–
description of calculation of regular price, multiply no of sand sacks by 2, multiply no of
gravel sacks by 2, multiply no of cement sacks by 3
–
output of regular price
–
description of calculating the number of special packs using the pack information (2
sacks of sand, 2 sacks of gravel and 1 sack of cement)
–
…….repeat until there are no more packs in the order (less than 2 sacks of sand or less
than 2 sacks of gravel or no sacks of cement
–
calculation of discount price and/or amount saved
–
output discount price and/or amount saved
© Cambridge International Examinations 2016
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Mark Scheme
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Cambridge IGCSE – May/June 2016
Page 4
Syllabus
0478
Paper
22
Section B
2
(i) 1 mark for each improvement
use FOR … NEXT instead of REPEAT … UNTIL
Move PRINT to after the end of the loop
Add error checking to check that the value input is positive
[3]
(ii) 3 marks maximum, 1 mark for each improvement correctly included.
Sample answer below
1 Total = 0
2
FOR Counter = 1 To 10
3
REPEAT
4
INPUT Num
5
UNTIL Num >0
6
Total = Total + Num
7 NEXT Counter
8 PRINT Total
[3]
3
Area
0
13.5
34.5
46.5
65
(2 marks)
1 mark 0, 13.5
1 mark for rest
Tins
0
Height
3
3
3
3
–1
7
(1 mark)
Width
5
7
5
7
0
Doors
1
0
0
1
0
(1 mark)
Windows
0
0
3
1
0
[4]
© Cambridge International Examinations 2016
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Cambridge IGCSE – May/June 2016
Page 5
4
Syllabus
0478
Paper
22
1 mark for each correct line, maximum 3 (zero correct 0, one correct 1, two correct 2, three or
four correct 3), each box must have only one connection.
Statement type
example
Assignment
FOR X ← 1 TO 10
Iteration
READ X
Input
PRINT X
Output
X ← Y + Z
[3]
5
6
7
– data structure (one—dimensional) array ……….
– ……… reason to simplify programming/ make programs shorter, etc.
[2]
– IF (… THEN … ELSE … ENDIF)
– CASE (… OF … OTHERWISE … ENDCASE)
[2]
(a) – 7
[1]
(b) – Brochure Number……..
– ….. Uniquely identifies each record/each Brochure Number different/no duplicates
[2]
(c) – Number of Seats – number/integer
– Price in $ – currency/real
[2]
(d) 1 mark for each correct result, 1 mark for the results in descending order of price
– Recliner sofa 1,200 RS23
– Recliner chair 600
RC01
© Cambridge International Examinations 2016
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Cambridge IGCSE – May/June 2016
Page 6
(e)
Syllabus
0478
Paper
22
Field:
Brochure
Number
Material
Colour
Price in $
Number of
Seats
Table:
SOFASELECT
SOFASELECT
SOFASELECT
SOFASELECT
SOFASELECT
Sort:
Show:
Criteria:
>2
or:
(1 mark)
(1 mark)
(1 mark)
(1 mark)
(1 mark)
[5]
© Cambridge International Examinations 2016
.
291
Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
0478/23
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2016
PRE-RELEASE MATERIAL
No Additional Materials are required.
* 6 0 1 9 0 0 5 9 9 2 *
This material should be given to the relevant teachers and candidates as soon as it has been received
at the Centre.
READ THESE INSTRUCTIONS FIRST
Candidates should use this material in preparation for the examination. Candidates should attempt the
practical programming tasks using their chosen high-level, procedural programming language.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 2 printed pages.
DC (ST) 124079
© UCLES 2016
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292
In preparation for the examination candidates should attempt the following practical tasks by writing
and testing a program(s).
The manager of a parcel delivery service needs a program to check the size and weight of parcels to
determine which parcels can be accepted for delivery.
Write and test a program for the manager.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Check the size and weight of a single parcel
Each parcel must obey the following rules to be accepted for delivery:
•
each dimension must be no more than 80 cm
•
the sum of the three dimensions must be no more than 200 cm
•
the weight of the parcel must be between one and ten kilograms inclusive
Input and store the weight and dimensions for one parcel. All the dimensions and the weight must be
validated on entry and an unsuitable parcel rejected.
Output if the parcel is accepted or rejected. If rejected, output all the reasons why the parcel was
rejected.
TASK 2 – Check a customer’s consignment of parcels
Input and store the number of parcels in the consignment. Calculate the number of parcels accepted
and the total weight of the parcels accepted. For each parcel that was rejected, output all the reasons
why that parcel was rejected.
Output the number of parcels accepted and the total weight of parcels accepted.
Output the number of parcels rejected.
TASK 3 – Calculate the price for a customer’s consignment of parcels
Extend TASK 2 to also calculate the price for each parcel, using the following rules:
•
1 kg to 5 kg inclusive costs $10
•
Each 100 grams over 5 kg, up to 10 kg, costs an extra $0.10
Your output should also include the price for each parcel accepted and the total price of the consignment.
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable
effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will
be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2016
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293
Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
* 2 6 3 2 1 1 0 4 5 6 *
0478/23
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 11 printed pages and 1 blank page.
DC (LK/SW) 124305
© UCLES 2016
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294
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release Material
The manager of a parcel delivery service needs a program to check the size and weight of parcels
to determine which parcels can be accepted for delivery.
Write and test a program for the manager.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Check the size and weight of a single parcel
Each parcel must obey the following rules to be accepted for delivery:
•
each dimension must be no more than 80 cm
•
the sum of the three dimensions must be no more than 200 cm
•
the weight of the parcel must be between one and ten kilograms inclusive
Input and store the weight and dimensions for one parcel. All the dimensions and the weight must
be validated on entry and an unsuitable parcel rejected.
Output if the parcel is accepted or rejected. If rejected, output all the reasons why the parcel was
rejected.
TASK 2 – Check a customer’s consignment of parcels
Input and store the number of parcels in the consignment. Calculate the number of parcels accepted
and the total weight of the parcels accepted. For each parcel that was rejected, output all the
reasons why that parcel was rejected.
Output the number of parcels accepted and the total weight of parcels accepted.
Output the number of parcels rejected.
TASK 3 – Calculate the price for a customer’s consignment of parcels
Extend TASK 2 to also calculate the price for each parcel, using the following rules:
•
1 kg to 5 kg inclusive costs $10
•
Each 100 grams over 5 kg, up to 10 kg, costs an extra $0.10
Your output should also include the price for each parcel accepted and the total price of the
consignment.
© UCLES 2016
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295
1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
For each of the variables that you have used to record dimensions of the parcels in Task 1,
state the name, type and its use.
Variable 1 name .................................................................................................................
Type ....................................................................................................................................
Use .....................................................................................................................................
Variable 2 name .................................................................................................................
Type ....................................................................................................................................
Use .....................................................................................................................................
Variable 3 name .................................................................................................................
Type ....................................................................................................................................
Use .................................................................................................................................[3]
(ii)
State two constants that you could have used for Task 1. Give the value that would be
assigned to each one.
Constant 1 name ................................................................................................................
Value 1 ...............................................................................................................................
Constant 2 name ................................................................................................................
Value 2 ...........................................................................................................................[2]
© UCLES 2016
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296
(b) Write an algorithm to complete Task 1, using either pseudocode, programming statements
or a flowchart.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
© UCLES 2016
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(c) Give three different data sets that could be used to check your validation rules for Task 1.
Explain why you chose each data set.
Data set 1 ..................................................................................................................................
Reason for choice ......................................................................................................................
...................................................................................................................................................
Data set 2 ..................................................................................................................................
Reason for choice ......................................................................................................................
...................................................................................................................................................
Data set 3 ..................................................................................................................................
Reason for choice ......................................................................................................................
...............................................................................................................................................[6]
(d) Explain how your program calculates the price for a consignment (part of Task 3). You may
include programming statements as part of your explanation.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
© UCLES 2016
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298
Section B
2
Read this section of program code that inputs 10 positive numbers and then outputs the smallest
number input.
1
2
3
4
5
6
7
8
Small = 1000
Counter = 0
REPEAT
INPUT Num
IF Num < Small THEN Small = Num
Counter = Counter + 1
UNTIL Counter = 10
PRINT Small
(i)
Identify three changes you would need to make to find the largest number input instead
of the smallest number.
1 .........................................................................................................................................
...........................................................................................................................................
2 .........................................................................................................................................
...........................................................................................................................................
3 .........................................................................................................................................
.......................................................................................................................................[3]
(ii)
Rewrite the program code with your changes.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[3]
© UCLES 2016
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3
A program will be written to store information about members of a swimming club.
The following membership details will be recorded:
•
Name
•
Gender
•
Status:
•
Senior
•
Junior
•
Fee
•
Team member (Yes or No)
(i)
Choose a suitable data type for each of the membership details to be recorded.
Membership details
Data type
Name
Gender
Status
Fee
Team member
[5]
(ii)
The swimming club has 50 members.
State the data structure that would be most suitable to use and give a reason for your
choice.
Data structure.....................................................................................................................
Reason ...............................................................................................................................
.......................................................................................................................................[2]
© UCLES 2016
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300
4
The flowchart below inputs the height of children who want to ride on a rollercoaster. Children
under 1.2 metres are rejected. The ride starts when eight children have been accepted.
67$57
5LGHUV
5HMHFW
,1387
+HLJKW
,V
+HLJKW
"
<HV
5HMHFW5HMHFW
1R
5LGHUV5LGHUV
1R
5LGHUV
"
<HV
287387
5HDG\WRJR 5HMHFW
(1'
© UCLES 2016
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301
Complete the trace table for the input data:
1.4, 1.3, 1.1, 1.3, 1.0, 1.5, 1.2, 1.3, 1.4, 1.3, 0.9, 1.5, 1.6, 1.0
Riders
Reject
Height
OUTPUT
[4]
© UCLES 2016
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02
5
REPEAT ... UNTIL is one type of loop structure.
Identify and describe two other types of loop structure that you could use when writing
pseudocode.
Loop structure 1 .........................................................................................................................
Description .................................................................................................................................
...................................................................................................................................................
Loop structure 2 .........................................................................................................................
Description .................................................................................................................................
...............................................................................................................................................[4]
© UCLES 2016
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03
6
A database, STAFFPHONE, was set up to show the telephone extension numbers for members of
staff working in a department store.
Name
Department
Extension number
Jane Smith
Toys
129
Sue Wong
Books
124
Toys
129
Amy Tang
Household
123
Joe Higgs
Books
124
Jane Smith
Shoes
125
Adel Abur
Shoes
125
Peter Patel
Toys
129
David Chow
(a) Explain why none of the fields in the database can be used as a primary key.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(b) State a field that could be added as a primary key.
...................................................................................................................................................
Give a reason for choosing this field.
...................................................................................................................................................
...............................................................................................................................................[2]
(c) Use the query-by-example grid below to provide a list of all members of staff, in alphabetical
order, grouped by department.
Field:
Table:
Sort:
Show:
Criteria:
or:
[5]
© UCLES 2016
0478/23/M/J/16
.
304
Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
COMPUTER SCIENCE
0478/23
May/June 2016
Paper 2
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2016 series for most Cambridge IGCSE®,
Cambridge International A and AS Level components and some Cambridge O Level components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 6 printed pages.
© UCLES 2016
[Turn over
.
Mark Scheme
305
Cambridge IGCSE – May/June 2016
Page 2
Syllabus
0478
Paper
23
Section A
1
(a) (i) Many correct answers, names must be meaningful. This is an example only.
Length, real/integer, length of parcel
Breadth, real/integer, breadth of parcel
Height, real/integer, Height of parcel
[3]
(ii) Several correct answers, they must be meaningful. These are examples only.
Dimension, 80
TotalDimension 200
MaxWeight 10.00
[2]
(b) Any 5 from:
– input length, breadth, height and weight
– check each dimension, not more than 80
– check total of dimensions, not more than 200
– check weight at least 1
– check weight not more than 10
– output parcel accepted (must be in appropriate position)
– output parcel rejected (must be in appropriate position)
– output all reasons for rejecting parcel (reason must follow test)
Max 5 marks
Sample Answer.
INPUT Length, Breadth, Height, Weight
IF Length <= 80 AND Breadth <= 80 AND Height <= 80 AND Weight >= 1
AND Weight <=10 AND Length + Breadth + Height <= 200 THEN
PRINT 'Parcel accepted'
ELSE
PRINT 'Parcel rejected'
IF Length > 80 OR Breadth > 80 OR Height > 80 THEN
PRINT 'At least one dimension too large'
ENDIF
IF Weight < 1 THEN
PRINT 'Parcel too light'
ENDIF
IF Weight > 10 THEN
PRINT 'Parcel too heavy'
ENDIF
ENDIF
© Cambridge International Examinations 2016
[5]
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Mark Scheme
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Cambridge IGCSE – May/June 2016
Syllabus
0478
Paper
23
(c) 1 mark for the data set and 1 mark for the matching reason all, data sets and reasons must
be different. There are many possible correct answers these are examples only.
Data set 30, 29, 28, 4
Reason – normal data; parcel should be accepted
Data set 80, 60, 60, 10
Reason – boundary data; parcel should be accepted
Data set – 85, 60, 60, 11
Reason – abnormal data; parcel should be rejected
[6]
(d) Maximum 4 marks in total, maximum 2 marks if only programming statements used.
Explanation (may include reference to programming statements)
– loop for number of parcels
– parcels 5 kg or less use standard price
– over 5 kg use weight to calculate price
– Correct calculation of price
– keep running total of consignment price
© Cambridge International Examinations 2016
[4]
.
Mark Scheme
307
Cambridge IGCSE – May/June 2016
Page 4
Syllabus
0478
Paper
23
Section B
2
(i) 1 mark for each change
Change variable name in every instance as needs to be meaningful e.g. Large
Set this variable to a low value
line 5: change comparison from < to >
[3]
(ii) 3 marks maximum, 1 mark for each change correctly included.
1
2
3
4
5
6
7
8
Large = 0
Counter = 0
REPEAT
INPUT Num
IF Num > Large THEN Large = Num
Counter = Counter + 1
UNTIL Counter = 10
PRINT Large
[3]
3
(i) Name type – string
Gender type – char/string
Status type – char/string
Fee type – real
Team member type – Boolean
[5]
(ii) Data Structure – several Arrays ……
………….Reason – to simplify programming/ make programs shorter/index can be used
to identify the same member across the arrays etc.
[2]
© Cambridge International Examinations 2016
.
Mark Scheme
308
Cambridge IGCSE – May/June 2016
Page 5
4
Riders
Reject
0
0
Height
1
1.4
2
1.3
1
Syllabus
0478
Paper
23
Output
1.1
3
1.3
2
1.0
4
1.5
5
1.2
6
1.3
7
1.4
8
1.3
Ready to go 2
(1 mark)
(1 mark)
(1 mark)
(1 mark)
[4]
5
– FOR (… TO … NEXT)…
– … a set number of iterations
– WHILE (… DO … ENDWHILE) …
– … used where the loop may never be executed/whilst a specified condition exists
[4]
6
(a) – all (fields) have (1 mark) duplicate entries (1 mark)
– none (of the fields) (1 mark) have unique entries(1 mark)
[2]
(b) – e.g. StaffNumber ….
– ….. Uniquely identifies each member of staff//no duplicates//different for each member of
staff
[2]
© Cambridge International Examinations 2016
.
Mark Scheme
309
Cambridge IGCSE – May/June 2016
Page 6
(c)
Field:
Department
Name
Table:
STAFFPHONE
STAFFPHONE
Sort:
Ascending
Ascending
Show:
(2 marks)
(2 marks)
Syllabus
0478
Paper
23
Criteri
a:
or:
(1 mark for correct order and number of fields shown)
[5]
© Cambridge International Examinations 2016
.
310
Cambridge International Examinations
Cambridge Ordinary Level
* 0 7 4 3 5 8 5 6 7 6 *
2210/12
COMPUTER SCIENCE
Paper 1 Theory
October/November 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 12 printed pages.
DC (AL) 135539
© UCLES 2016
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311
1
(a) Give two reasons why a programmer would choose to write code in a low-level language.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
(b) High-level languages require either an interpreter or a compiler to translate the program.
The table below lists a number of statements about language translators.
Tick (3) to show which statements refer to interpreters and which refer to compilers.
Statements
Interpreter (3)
Compiler (3)
Translates the source code into machine code
all at once
Produces an executable file in machine code
Executes a high-level language program one
instruction at a time
Once translated, the translator does not need to
be present for the program to run
An executable file is produced
[5]
2
State four functions of an operating system.
1 .......................................................................................................................................................
2 .......................................................................................................................................................
3 .......................................................................................................................................................
4 .......................................................................................................................................................
[4]
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3
(a) Explain what is meant by:
(i)
Serial data transmission
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
(ii)
Parallel data transmission
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
(b) A computer in a factory is connected to a printer. The printer is located in an office 1 km away
from the factory.
Identify which data transmission method would be most suitable for this connection.
...................................................................................................................................................
Give two reasons for your choice.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
© UCLES 2016
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4
Nine bytes of data are transmitted from one computer to another. Even parity is used. An additional
parity byte is also sent.
The ten bytes arrive at the destination computer as follows:
parity bit
bit 2
bit 3
bit 4
bit 5
bit 6
bit 7
bit 8
byte 1
1
1
1
0
1
1
1
0
byte 2
0
0
0
0
0
1
0
1
byte 3
0
1
1
1
1
0
0
0
byte 4
1
1
0
0
0
0
0
0
byte 5
1
0
1
1
1
1
1
0
byte 6
0
1
0
1
1
0
0
1
byte 7
0
1
1
1
0
0
1
1
byte 8
0
0
1
1
0
1
1
0
byte 9
1
1
0
0
0
0
1
1
parity byte
0
0
1
0
0
0
1
0
One of the bits was corrupted during the data transmission.
(a) Circle the corrupt bit in the corrupt byte in the table above.
[1]
(b) Explain how the corrupted bit was found.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
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5
A computer uses an 8-bit register.
The 8-bit register contains binary integers.
(a) Write the denary (base 10) value represented by:
128
64
32
16
8
4
2
1
0
1
1
1
0
0
0
0
...............................................................................................................................................[1]
(b) All the bits in the register are shifted one place to the right as shown below.
0
1
1
1
0
0
0
0
0
0
1
1
1
0
0
0
Write the denary number that is represented after this shift.
...............................................................................................................................................[1]
(c) State the effect the shift to the right had on the original denary number from part (a).
...............................................................................................................................................[1]
(d) The original number in part (a) is shifted three places to the right.
(i)
Show the new binary number:
[1]
(ii)
Write the equivalent denary number.
.......................................................................................................................................[1]
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(e) Describe the problems that could be caused if the original binary number in part (a) is shifted
five places to the right.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
6
Four computer terms and eight descriptions are shown below.
Draw lines to connect each computer term to the correct description(s).
Computer term
Description
Data can be read but not altered
Arithmetic and logic
unit (ALU)
Carries out operations such as
addition and multiplication
Stores bootstrap loader and BIOS
Control unit
Fetches each instruction in turn
Carries out operations such as
AND, OR, NOT
Random access
memory (RAM)
Stores part of the operating system
currently in use
Read only memory
(ROM)
Stores data currently in use
Manages execution of each
instruction
[4]
© UCLES 2016
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316
7
(a) Complete the truth tables and name the single logic gate that could replace each logic circuit:
(i)
A
A
B
0
0
0
1
1
0
1
1
Working space
X
X
B
Single logic gate ............................................................................................................[3]
(ii)
A
X
B
A
B
0
0
0
1
1
0
1
1
Working space
X
Single logic gate ............................................................................................................[3]
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317
(b) (i)
Draw a logic circuit to represent the following logic statement:
X = 1 if (A = 1 AND B = 1) OR ( (B = NOT 1) AND C = 1)
A
B
X
C
[4]
(ii)
Complete the truth table for the logic statement in part (b)(i).
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Working space
X
[4]
© UCLES 2016
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318
8
Identify whether the four statements about file compression are correct by writing TRUE or FALSE
in the following table.
Statement
TRUE or FALSE
MIDI files store the actual music notes in a compressed format
JPEG files are examples of lossless file compression
MP3 files are, on average, 90% smaller than the music files
stored on a CD
MP4 files are examples of lossy file compression
[4]
9
(a) Explain what is meant by a denial of service attack.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(b) Name and describe two other potential security threats when using the Internet.
Security threat 1 .......................................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Security threat 2 .......................................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[4]
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19
10 (a) Describe what is meant by HTML.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
(b) The following URL is typed in:
http://www.cie.org.uk/ComputerSciencePapers
This URL is composed of three parts.
State the part of this URL that is the:
File name ..................................................................................................................................
Protocol ....................................................................................................................................
Web server name .....................................................................................................................
[3]
© UCLES 2016
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20
11
A security system is installed in a house. A hexadecimal number is entered to activate or deactivate
the alarm.
(a) The alarm code is set to hexadecimal number 2 A F
Show how this number would be stored in a 12-bit binary register.
[3]
(b) Identify two sensors that the security system could use to detect intruders.
Describe how each sensor could be used in the security system.
Sensor 1 ...................................................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Sensor 2 ...................................................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[6]
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21
12 Explain the differences between freeware and free software.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
......................................................................................................................................................[4]
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2016
2210/12/O/N/16
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Cambridge International Examinations
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/12
Paper 1
October/November 2016
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the October/November 2016 series for most
®
Cambridge IGCSE , Cambridge International A and AS Level components and some Cambridge O Level
components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This document consists of 10 printed pages.
© UCLES 2016
[Turn over
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Mark Scheme
323
Cambridge O Level – October/November 2016
Page 2
(a) Any two from:
–
–
–
Syllabus
2210
Paper
12
direct access to computer processor / special hardware // machine dependent
instructions
uses up less memory
can increase the speed of processing a program // executes instructions faster
[2]
(b)
Interpreter (9)
Statements
Compiler (9)
Translates the source code into machine code
all at once
9
Produces an executable file in machine code
9
Executes a high-level language program one
instruction at a time
9
Once translated, the translator does not need to be
present for the program to run
9
An executable file is produced
9
[5]
2
Any four from:
–
–
–
–
–
–
–
–
–
–
–
–
Provides a user interface
Handles interrupts / errors
Memory management
File management
Manages peripherals (inputs/outputs)
Provides security methods
Allows multitasking
Manages multiprogramming
Enables batch processing
Manages software installation / removal
Allows creation of multiple accounts
Levels of access
[4]
© UCLES 2016
3
.
Mark Scheme
324
Cambridge O Level – October/November 2016
Page 3
(a) (i) Any two from:
Syllabus
2210
Paper
12
serial
–
–
–
one bit sent at a time // bits sent sequentially
over a single wire
synchronous or asynchronous
[2]
(ii) Any two from:
parallel
–
–
–
several bits / a byte sent at a time
using many / multiple wires
synchronous
[2]
(b)
–
serial
Any two from:
–
–
–
–
–
serial data transmission more reliable over long distances
less likely for the data to be skewed/out of synchronisation
less interference as only a single wire
it is a cheaper connection as only single wire needed // cheaper to set up
a fast connection is not required as a printer is limited by its printing speed
[3]
4
(a) Intersection of Row 7 and column 4 circled
(b) –
–
[1]
Row (byte number) 7 has an odd number of 1s (five 1s)
Column (bit number) 4 has an odd number of 1s (five 1s)
[2]
© UCLES 2016
.
Mark Scheme
325
Cambridge O Level – October/November 2016
Page 4
5
(a) 112
Syllabus
2210
Paper
12
[1]
(b) 56
[1]
(c) divided by 2 // value 112 was halved // multiplied by 0.5
[1]
(d) (i)
0
0
0
0
1
1
1
0
[1]
(ii) 14
[1]
(e) Any two from:
–
–
–
–
run out of places to the right of register / at the end of register
right-most 1 would be lost
number would become 3 instead of 3.5
loss of precision
[2]
© UCLES 2016
Page 5
6
.
Mark Scheme
326
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
12
1 mark for both correct lines from each computer term.
[4]
© UCLES 2016
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7
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Mark Scheme
327
Cambridge O Level – October/November 2016
(a) (i) 2 marks for 4 correct outputs,
1 mark for 2 correct outputs
Syllabus
2210
Paper
12
1 mark for correct gate
A
B
Working space
X
0
0
0
0
1
0
1
0
0
1
1
1
AND gate
[3]
(ii) 2 marks for 4 correct outputs
1 mark for 2 correct outputs
1 mark for correct gate
A
B
Working space
X
0
0
0
0
1
1
1
0
1
1
1
1
OR gate
[3]
© UCLES 2016
Page 7
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Mark Scheme
328
Cambridge O Level – October/November 2016
(b)(i) 1 mark per correct section.
Syllabus
2210
Paper
12
1 mark
1 mark
1 mark
1 mark
[4]
(ii) 4 marks for 8 correct outputs
3 marks for 6 correct outputs
2 marks for 4 correct outputs
1 mark for 2 correct outputs
A
B
C
Working space
X
0
0
0
0
0
0
1
1
0
1
0
0
0
1
1
0
1
0
0
0
1
0
1
1
1
1
0
1
1
1
1
1
[4]
© UCLES 2016
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329
Cambridge O Level – October/November 2016
Page 8
8
Statement
Syllabus
2210
Paper
12
TRUE or FALSE
MIDI stores the actual music notes in a compressed format
FALSE
JPEG files are examples of lossless file compression
FALSE
MP3 files are, on average, 90% smaller than the music files
stored on a CD
TRUE
MP4 files are examples of lossy file compression
TRUE
[4]
9
(a) Any two from:
–
–
–
–
a large number of requests are sent to the network/server all at once
designed to flood a network/server with useless traffic/requests
the network/server will come to a halt/stop trying to deal with all the traffic/requests
prevents users from gaining access to a website/server
[2]
(b) 1 mark for each security threat and 1 mark for matching description
Security threat
Description
Viruses
– software that replicates
– causes loss/corruption of data // computer may “crash”/run
slow
Hacking/cracking
– illegal/ unauthorised access to a system/data
Phishing
– a link/attachment sends user to fake website (where personal
data may be obtained)
Pharming
– malicious code installed on user’s hard drive / computer
– user is redirected to a fake website (where personal data may
be obtained)
Spyware/key logger
– send/relay key strokes to a third party
[4]
© UCLES 2016
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Mark Scheme
330
Cambridge O Level – October/November 2016
Page 9
10 (a) Any three from:
–
–
–
–
Syllabus
2210
Paper
12
hyper text mark-up language
uses both structure and presentation
web-authoring language/software // used to create websites/webpages
uses tags to define e.g. colour / font / graphics / layout
[3]
(b)
File name:
ComputerSciencePapers
Protocol:
http(://)
Web server name:
www.cie.org.uk
[3]
11 (a) 1 mark per nibble
0010
1010
1111
[3]
(b) 1 mark for identification of each sensor, max 2 for each description
Infrared/motion sensor
–
–
–
–
–
Receives infrared rays/heat
Sends data to microprocessor
Receives microwaves
Placed in the corner of a room, across a doorway
Used to detect the heat of an intruder // used to detect if an infrared beam has been
broken by an intruder
Pressure sensor
–
–
–
–
Receives current if circuit created // stops receiving current if circuit is broken
Sends data to microprocessor
Placed on a window/door, at the entrance
Used to detect a change in pressure
[6]
© UCLES 2016
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12 Any four from:
–
–
–
–
–
.
Mark Scheme
331
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
12
Freeware needs owner’s permission to share/copy/amend whereas free software can be
shared/copied/amended without permission
Freeware the owner retains copyright / is subject to copyright whereas free software the
owner releases copyright/ is not subject to copyright
Freeware is normally provided without a fee whereas free software a fee may be charged
Freeware is distributed without the source code whereas free software is distributed with the
source code
Freeware can be restricted in use e.g. non-commercial whereas free software can be used
without restriction
NOTE: The question asks candidates to explain the differences, so each mark needs to have a
comparison.
[4]
© UCLES 2016
.
332
Cambridge International Examinations
Cambridge Ordinary Level
* 2 2 0 3 8 2 8 9 7 8 *
2210/13
COMPUTER SCIENCE
Paper 1 Theory
October/November 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 14 printed pages and 2 blank pages.
DC (SLM) 135989
© UCLES 2016
[Turn over
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333
1
To process an instruction, a central processing unit (CPU) goes through a cycle that has three
main stages.
Name each stage in this cycle.
Stage 1 ................................................................................
Stage 2 ................................................................................
Stage 3 ................................................................................
[3]
2
Name each of the potential security issues described in the five statements below:
Statement
Security issue
The act of gaining unauthorised access to
a computer system
..................................................................................
Program code that can replicate itself with
the intention of deleting or corrupting files
stored in a computer
..................................................................................
A small file sent by a web server to a web
browser; every time the user visits the
website, data about user preferences is
collected
..................................................................................
The act of illegally changing the source
code of a program so that it can be
exploited for another use
..................................................................................
Malicious code installed on a user’s hard
drive or a web server which redirects
the user to a fake website without their
knowledge
..................................................................................
[5]
© UCLES 2016
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3
Five computer terms and seven descriptions are shown below.
Draw a line to connect each computer term to its correct description.
Computer term
Description
Several bits of data sent down several
wires, in both directions, but not at the
same time
Serial, simplex data
transmission
Several bits of data sent down several
wires, in both directions, at the same
time
Parallel, half-duplex
data transmission
Parity check
An even or odd number of bits set to 1
in a byte, used to check if the byte has
been transmitted correctly
One bit sent at a time, over a single wire
in one direction only
An additional digit placed at the end of a
number to check if the number has been
entered correctly
Automatic repeat
request (ARQ)
A value transmitted at the end of a block
of data; it is calculated using the other
elements in the data stream and is used
to check for transmission errors
Checksum
© UCLES 2016
An error detection method that uses
response and time out when transmitting
data; if a response is not sent back to
the sender in an agreed amount of time,
then the data is re-sent
2210/13/O/N/16
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335
4
The Henslows Diner is a local restaurant.
(a) Staff currently use a keyboard to input a customer food order into a computer. The food order
is then sent to the kitchen.
State two disadvantages of using a keyboard to input a customer food order.
1 ................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
[2]
(b) A concept keyboard has a flat surface that is overlaid with images of food items available
from the restaurant menu. Staff can click on an image to add the food item to a customer food
order.
The Henslows Diner wants to change to a concept keyboard to input customer food orders.
Explain two benefits of making this change.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[4]
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336
(c) The Henslows Diner stores personal data on a computer. This computer is connected to the
Internet to allow the data to be backed up.
There is currently one security method in place to protect the data on the computer from
unauthorised access. This is a password.
Give two other security methods that could be added to improve the security of the data.
Describe how each method will keep the data safe.
Security method 1 .....................................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Security method 2 .....................................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[4]
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5
Three switches, A, B and C, each send values of 0 or 1 to a logic circuit. Value X is output from the
logic circuit.
Switch A
Switch B
Logic circuit
Output X
Switch C
Output X has a value of 1 depending on the following conditions:
Switch A sends value 1 AND Switch B sends value 0
OR
Switch B sends value 1 AND Switch C sends value 0
(a) Draw a logic circuit to represent the conditions above.
A
B
X
C
[5]
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(b) Complete the truth table for the conditions given at the start of question 5.
Working space
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
X
[4]
(c) A microprocessor regularly samples the output, X. Each sample value is stored in an 8-bit
register as shown below. One bit of this register is reserved as a parity bit.
Five consecutive output values of 1 indicate a fault condition.
Identify which of the following registers shows a fault condition.
Parity bit
1
1
1
1
1
0
0
1
Register Y
0
1
0
1
1
1
1
1
Register Z
Register .............................................[1]
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(d) When eight bytes of data have been collected, they are transmitted to a computer 100 km
away. Parity checks are carried out to identify if the data has been transmitted correctly. The
system uses even parity and column 1 is the parity bit.
The eight bytes of data are sent together with a ninth parity byte:
parity
bit
column
2
column
3
column
4
column
5
column
6
column
7
column
8
byte 1
1
0
0
0
0
1
0
0
byte 2
1
1
1
1
0
0
1
1
byte 3
0
1
0
0
1
0
0
0
byte 4
0
1
1
1
0
0
0
1
byte 5
1
0
0
0
1
1
1
1
byte 6
0
0
0
0
0
0
0
0
byte 7
1
1
1
0
1
0
0
0
byte 8
1
0
0
0
1
1
1
0
parity
byte
1
0
1
1
0
1
1
1
(i)
Identify which of the eight bytes contains an error.
byte ...............................................................................................................................[1]
(ii)
Identify which column contains an error.
column ...........................................................................................................................[1]
(iii)
The incorrect bit is indicated where the byte number and column cross.
Give the corrected byte.
[1]
(iv)
Calculate the denary value of the corrected byte.
...........................................................................................................................................
.......................................................................................................................................[1]
(v)
Considering the fault condition given in part (c), explain why it is very important that the
incorrect bit is located and corrected.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
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6
High-level or low-level languages can be used when writing a computer program.
State two advantages of using a high-level language and two advantages of using a low-level
language.
High-level language advantage 1 ....................................................................................................
..........................................................................................................................................................
High-level language advantage 2 ....................................................................................................
..........................................................................................................................................................
Low-level language advantage 1 .....................................................................................................
..........................................................................................................................................................
Low-level language advantage 2 .....................................................................................................
..........................................................................................................................................................
[4]
7
Modern Liquid Crystal Display (LCD) monitors use Light-Emitting Diode (LED) backlit technology.
Give four benefits of using LED technology.
1 .......................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
2 .......................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
3 .......................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
4 .......................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[4]
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8
Four descriptions about compilers and interpreters are shown below.
Draw lines to indicate which descriptions refer to a compiler and which descriptions refer to an
interpreter.
Description
It is more difficult to debug the
code since one error can
produce many other associated
errors.
The speed of execution of
program loops is slower.
Compiler
It produces fast, executable
code that runs directly on the
processor.
Interpreter
It is easier to debug the code
since an error is displayed as
soon as it is found.
[4]
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42
9
A security light is controlled by sensors and a microprocessor.
Describe how the sensors and microprocessor interact to switch on the security light when an
intruder is detected.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
......................................................................................................................................................[6]
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43
10 (a) A manufacturer of aeroplane engines assigns a denary identification number (ID) to each
engine.
One engine has the ID:
(i)
0431
Convert this denary number to a 12-bit binary format.
[2]
(ii)
Show how this number would be represented in hexadecimal.
...........................................................................................................................................
...........................................................................................................................................
[3]
(b) The current status of the engine is sent to a computer in the aeroplane.
Each piece of data collected is 8 bytes in size. Data collection occurs every 30 seconds.
Calculate the number of kilobytes that would be needed to store the data collected during a
10-hour flight. Show your working.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
................................................. kilobytes
[3]
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44
(c) At the end of the flight, all of the data are sent to the aeroplane engine manufacturer using the
Internet.
The computer in the aeroplane has a MAC address and an IP address.
State what is meant by these two terms.
MAC address ............................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
IP address .................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
(d) When sending this data, security is very important. Data are sent over the Internet using
Transport Layer Security (TLS) protocol.
Name the two layers that make up TLS.
1 ................................................................................................................................................
2 ................................................................................................................................................
[2]
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11
Explain why ethics are important when using computers.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
......................................................................................................................................................[6]
© UCLES 2016
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Cambridge International Examinations
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/13
October/November 2016
Paper 1
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the October/November 2016 series for most
®
Cambridge IGCSE , Cambridge International A and AS Level components and some Cambridge O Level
components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This document consists of 9 printed pages.
© UCLES 2016
[Turn over
Page 2
1
2
In any order:
– Fetch
– Decode
– Execute
–
–
–
–
–
.
Mark Scheme
347
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
13
[3]
Hacking
Virus
Cookies
Cracking
Pharming
[5]
© UCLES 2016
Page 3
3
.
Mark Scheme
348
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
13
[5]
© UCLES 2016
Page 4
4
.
Mark Scheme
349
Cambridge O Level – October/November 2016
(a) Any two from:
–
–
–
Syllabus
2210
Paper
13
Easy to make a mistake
Can be slow if not trained
Dirt/food can get into keys
[2]
(b) Any two with identification and explanation from:
–
–
–
–
–
–
–
–
Fewer typing errors may be made …
… because one button is pressed to order an item
Speed up the time to enter an order …
… because fewer buttons are pressed to complete the order
May require less training …
… because it is easier to identify an order item from its image rather than typing it
Can stop dirt/food damage …
… normally has a protective layer // because there are no keys for dirt/food to get into
[4]
(c) 1 mark for security measure, 1 mark for description.
Any two from:
–
–
Encryption
If the data is accessed or stolen it will be meaningless
–
–
Biometric device
Can help prevents unauthorised access to the system (only award once)
–
–
–
–
Firewall
Can alert to show unauthorised access attempt on the system
Can help prevent unauthorised access to the system (only award once)
Can help protect against viruses and malware entering the system
–
–
Anti-spyware
Can stop the keys being logged that, when analysed, would reveal the password to
the data
© UCLES 2016
[4]
Page 5
5
.
Mark Scheme
350
Cambridge O Level – October/November 2016
(a) 1 mark per correct section.
Syllabus
2210
Paper
13
A
X
B
C
[5]
(b) 4 marks for 8 correct values
3 marks for 6 correct values
2 marks for 4 correct values
1 mark for 2 correct values
A
B
C
0
0
0
0
0
0
1
0
0
1
0
1
0
1
1
0
1
0
0
1
1
0
1
1
1
1
0
1
1
1
1
0
Working space
X
[4]
© UCLES 2016
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Mark Scheme
351
Cambridge O Level – October/November 2016
(c) Register Z
Syllabus
2210
(d) (i) (byte) 5
Paper
13
[1]
[1]
(ii) (column) 4
[1]
(iii) corrected byte is: 1 0 0 1 1 1 1 1
[1]
(iv) that gives the value: 1 5 9
(follow through applies)
[1]
(v) Any two from:
–
–
6
The byte would be transmitted without having 5 consecutive 1’s
The fault condition would not be recognised
[2]
Any two from:
High level language
–
–
–
–
easier/faster to write code as uses English-like statements
easier to modify as uses English-like statements
easier to debug as uses English-like statements
portable language code
Any two from:
Low level language
–
–
–
7
can work directly on memory locations
can be executed faster
translated program requires less memory
[4]
Any four from:
–
–
–
–
–
–
reaches maximum brightness quickly
colours are vivid
good colour definition/contrast can be achieved
screens can be thinner/thin
more reliable as LED’s are long lasting
consume very little/less energy
© UCLES 2016
[4]
Page 7
.
Mark Scheme
352
Cambridge O Level – October/November 2016
8
Syllabus
2210
Paper
13
It is more difficult to debug the
code since one error can
produce many other
associated errors
The speed of execution of
program loops is slower.
Compiler
It produces fast, executable
code that runs directly on the
processor
Interpreter
It is easier to debug the code
since an error is displayed as
soon as it is found.
[4]
© UCLES 2016
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Mark Scheme
353
Cambridge O Level – October/November 2016
Any six from:
–
–
–
–
–
–
–
–
–
–
–
–
Syllabus
2210
Paper
13
infrared / motion / pressure (sensor) // sensor detects movement/pressure
signals/data sent (continuously) to microprocessor
converted from analogue to digital (using ADC)
microprocessor compares value with those stored in memory
if sensor value does not match the stored value(s) …
… signal sent to switch on the light
… signal sent to keep the light on
… light remains on for a period of time (30 seconds)
if sensor value matches the stored value(s) …
… light will remain off
… will turn off after period of time (30 seconds)
works in a continues loop
[6]
10 (a) (i) 2 marks for 3 correct binary conversions, 1 mark for 2 correct binary conversions
0
0
0
1
1
0
1
0
1
1
1
[2]
1
(ii) 1 mark for each correct hex value converted
1AF
[3]
(b) 2 marks for working + 1 mark for correct answer
Working
– 1200 × 8 = 9600 (bytes)
– 9600/1024 or 9600/1000
Answer
– 9.4 or 9.6 kilobytes
[3]
(c) Any one from:
MAC address
–
–
–
–
Media Access Control (address)
unique number that identifies a device (connected to the Internet)
address is made up of manufacturer id + serial number of device
address is allocated by the manufacturer
Any one from:
IP address
–
–
–
–
–
Internet Protocol (address)
location/address of a device on the Internet
address is unique for given Internet session
address is supplied when a device connects to the Internet
address is allocated by the network
© UCLES 2016
[2]
Page 9
(d) –
–
.
Mark Scheme
354
Cambridge O Level – October/November 2016
record (layer)
handshake (layer)
Syllabus
2210
Paper
13
[2]
11 Any six from:
– Help stop the misuse of computers
– The use of computers needs to be governed
– Help keep users safer when using computers
– Provides rules for using computers
– Help stop intellectual property theft
– Helps prevent the misuse of personal information
– Reference to laws (relevant example)
– Reference to security issues (relevant example)
NOTE: Answer must refer to the importance of ethics and be more than a description of
ethics.
© UCLES 2016
[6]
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355
Cambridge International Examinations
Cambridge Ordinary Level
* 3 9 5 3 9 3 5 0 7 5 *
2210/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
October/November 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 11 printed pages and 1 blank page.
DC (CW/FD) 126911/1 R
© UCLES 2016
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356
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release Material
The manager of a supermarket needs a program to record donations to charity. Each customer has
the choice of three charities to donate to, and 1% of their shopping bill will be donated to the chosen
charity.
Write and test a program for the manager.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Set up the donation system
Set up a routine that allows:
•
the names of three charities to be input and stored
•
the charity names to be displayed with a number (1, 2 or 3) beside each name
•
a choice of 1, 2 or 3 to be entered to choose the charity, all other entries rejected
•
the value of a customer’s shopping bill to be entered
•
the donation to be calculated
•
three totals to be set to zero ready to total each charity donation
TASK 2 – Record and total each donation
For a customer’s shopping bill:
•
input a charity choice of 1, 2 or 3
•
input the value of a customer’s shopping bill
•
calculate the donation
•
add the donation to the appropriate total
Output the name of the charity and the amount donated.
TASK 3 – Show the totals so far
Extend TASK 2 to accept:
•
donations from more customers
•
a charity choice of -1 to show the totals so far
Display the charities’ names and the totals in descending order of totals.
Calculate a grand total of all three totals.
Output ‘GRAND TOTAL DONATED TO CHARITY’ and the amount of the grand total.
© UCLES 2016
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1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
For three of the variables that you have used in Task 1, state the name, type and its use.
Variable 1 name ................................................................................................................
Type ...................................................................................................................................
Use ....................................................................................................................................
Variable 2 name ................................................................................................................
Type ...................................................................................................................................
Use ....................................................................................................................................
Variable 3 name ................................................................................................................
Type ...................................................................................................................................
Use ............................................................................................................................... [3]
(ii)
Name and describe the data structure(s) that you have used to store the donation totals
for each charity. Explain why you chose your data structure(s).
Name of data structure(s) .................................................................................................
Description ........................................................................................................................
...........................................................................................................................................
Reason ..............................................................................................................................
...................................................................................................................................... [3]
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358
(b) Write an algorithm to complete Task 2, using either pseudocode, programming statements
or a flowchart. You can assume that Task 1 has been completed.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [5]
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359
(c) Explain how you show the totals so far (Task 3). You may include programming statements as
part of your explanation.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [6]
(d) Explain how you would change your solution for Task 1 to allow the number of charities to be
set to two, three or four by the manager.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [3]
© UCLES 2016
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360
Section B
2
Read this section of program code that inputs positive numbers, discards any negative numbers
and then outputs the average. An input of zero ends the process.
1
2
3
4
5
6
7
8
9
10
11
Total = 0
Counter = 100
REPEAT
REPEAT
INPUT Num
UNTIL Num < 0
Total = Total + 1
Counter = Counter + Num
UNTIL Num = 0
Average = Total / (Counter - 1)
Print Average
There are four errors in this code.
Locate these errors and suggest a correction to remove each error.
Error 1 ..............................................................................................................................................
Correction .........................................................................................................................................
..........................................................................................................................................................
Error 2 ..............................................................................................................................................
Correction .........................................................................................................................................
..........................................................................................................................................................
Error 3 ..............................................................................................................................................
Correction .........................................................................................................................................
..........................................................................................................................................................
Error 4 ..............................................................................................................................................
Correction .........................................................................................................................................
..................................................................................................................................................... [8]
© UCLES 2016
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361
3
The flowchart below inputs an integer. The predefined function DIV gives the value of the division,
for example Z ← 11 DIV 3 gives the value Z = 3. The predefined function MOD gives the value
of the remainder, for example Z ← 11 MOD 3 gives the value Z = 2.
67$57
,1387;
,V;!
"
<HV
$
%
1R
;',9
;02'
287387;
(1'
287387%
;
$
Complete a trace table for each of the two input values 33 and 75.
Trace table for input value 33
X
A
B
OUTPUT
A
B
OUTPUT
Trace table for input value 75
X
[4]
© UCLES 2016
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362
4
IF ... THEN ... ELSE ... ENDIF and CASE ... OF ... OTHERWISE ... ENDCASE
are two different conditional statements that you can use when writing pseudocode.
Explain, using examples, why you would choose to use each conditional statement.
Example 1 ........................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Reason for choice ............................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Example 2 ........................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Reason for choice ............................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [6]
© UCLES 2016
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9
363
Question 5 begins on page 10.
© UCLES 2016
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64
5
A database, PLAYPRODUCTION, was set up to show the performance dates, prices and number
of seats available at a theatre specialising in Shakespeare productions.
Performance
Date
Number
Seats
Stalls
Number
Seats
Circle
Price Stalls
Seats $
Price Circle
Seats $
As You Like It
01/07/2016
120
90
20.00
30.00
As You Like It
02/07/2016
85
45
30.00
40.00
As You Like It
09/07/2016
31
4
30.00
40.00
Macbeth
14/07/2016
101
56
25.00
35.00
Macbeth
15/07/2016
50
34
25.00
35.00
Macbeth
16/07/2016
12
5
35.00
50.00
Julius Caesar
22/07/2016
67
111
20.00
20.00
Julius Caesar
23/07/2016
21
24
15.00
15.00
A Comedy of Errors
30/07/2016
45
36
35.00
45.00
Play
(a) Give the number of fields that are in each record.
.............................................................................................................................................. [1]
(b) State the data type you would choose for each of the following fields.
Play ..........................................................................................................................................
Number Seats Stalls ...............................................................................................................
Price Stalls Seats $ ............................................................................................................ [3]
(c) The query-by-example grid below selects all the productions with more than 100 seats left in
either the stalls or the circle.
Field: Play
Performance Date
Number Seats Stalls
Number Seats Circle
Table: PLAYPRODUCTION
PLAYPRODUCTION
PLAYPRODUCTION
PLAYPRODUCTION
Sort: Ascending

Show:

Criteria:
> 100
or:
> 100
Show what would be output from the query-by-example.
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [3]
© UCLES 2016
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65
(d) Complete the query-by-example grid below to select all the productions with at least six seats
left in the circle and show the Play, Performance Date and Price Circle Seats $ in Performance
Date order.
Field:
Table:
Sort:
Show:
Criteria:
or:
[5]
© UCLES 2016
2210/22/O/N/16
.
366
Cambridge International Examinations
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/22
October/November 2016
Paper 2
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the October/November 2016 series for most
®
Cambridge IGCSE , Cambridge International A and AS Level components and some Cambridge O Level
components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This document consists of 6 printed pages.
© UCLES 2016
[Turn over
.
Page 2
Mark Scheme
367
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
22
Section A
1
(a) (i) Many correct answers, they must be meaningful. This is an example only.
– Choice, integer, choice of charity
– Cost, real, cost of shopping
– Donation, real, donation calculated from cost of shopping
[3]
(ii) – Array
– a set of (similar) variables grouped together// description or array declaration applied
to the scenario e.g. DonationTotals[1:3]
– allows for more efficient programing e.g. use of indices//each charity total can be
identified by an index
or
– List
– a set of variables grouped together// description or list declaration applied to the
scenario e.g. DonationTotals[]
– allows for more efficient programing e.g. use of a loop to update each charity
or
– Variables
– storage locations that can be changed// description or declaration applied to the
scenario e.g. DonationTotal1, DonationTotal2 and DonationTotal3
– e.g. as there are only 3 charities so there is no need to use an array
[3]
(b) Any five from:
– Prompt for input of charity choice // prompt for input of value of shopping
– input charity choice
– check for input of 1, 2, or 3
– input value of shopping
– calculate donation
– add donation to the appropriate total
– output name of charity and amount/total amount donated
[5]
Sample Answer.
REPEAT
PRINT 'Please enter choice of charity 1, 2. or 3 '
INPUT Choice
UNTIL Choice = 1 or Choice = 2 or Choice = 3
PRINT 'Please enter value of shopping bill '
INPUT BillValue
Donation BillValue * 0.01
Total (Choice) Total (Choice) + Donation
PRINT 'Charity ', CharityName (Choice), ' has received a donation
of ', Donation
© UCLES 2016
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Mark Scheme
368
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
22
(c) Maximum six marks in total for question part
Description (may include reference to program statements)
– when charity choice = -1
– display total donation for each charity …
– … with corresponding charity name…
– description of method for selecting descending order of totals
– evidence that the method works
– calculate grand total from 3 totals / sum of all donations
– output ‘GRAND TOTAL DONATED TO CHARITY’ and grand total
[6]
(d) Any three from:
– input number of charities
– store the number of charities as a variable
– change the upper value of the choice input
– change the array bounds for total donations etc.// add new variables to hold extra values
– the need to change the code…
– … to allow for differing number of charities
[3]
© UCLES 2016
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Mark Scheme
369
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
22
Section B
2
1 mark for identifying each error, 1 mark for the corresponding change
– line 2 or Counter = 100
– Counter = 0
– line 6 or UNTIL Num < 0
– UNTIL Num >= 0
– line 7 or Total = Total + 1
– Total = Total + Num
– line 8 or Counter = Counter + Num
– Counter = Counter + 1
3
[8]
Trace table for input value 33
X
A
B
OUTPUT
33
4
1
1
4
Å
4
Æ
(1 mark)
(1 mark)
Trace table for input value 75
X
A
B
OUTPUT
75
9
3
3
9
1
1
1
1
Å
1
(1 mark)
Æ
(1 mark)
[4]
© UCLES 2016
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Mark Scheme
370
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
22
For each example: 1 mark for correct structure, 1 mark for appropriate content, 1 mark for
the reason. There are many correct answers these are only examples
IF X > 0 AND X <= 10
THEN PRINT 'In Range'
ELSE PRINT 'Out of Range'
ENDIF
– e.g. checking a condition that may be complex//uses relational operators// checking for a range
of values// only 2 options
CASE X OF
1 : PRINT 'Option 1'
2 : PRINT 'Option 2'
3 : PRINT 'Option 3'
OTHERWISE PRINT 'Incorrect choice'
ENDCASE
– e.g. checking for discrete/large number/more than 2 of values
[6]
5
(a) – 6
[1]
(b)
– Play
– No Seats Stalls
– Price Stalls Seats $
text
number
currency
[3]
(c) 1 mark for correct plays, 1 mark for correct dates with each play and no extra fields or
text, 1 mark for the order
As You Like It
01/07/2016
Julius Caesar
22/07/2016
Macbeth
14/07/2016
[3]
© UCLES 2016
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Cambridge O Level – October/November 2016
(d)
Field: Play
Table: PLAYPRODUCTION
Sort:
Show:
Syllabus
2210
Paper
22
Performance Date
Number Seats Circle
Price Circle Seats $
PLAYPRODUCTION
PLAYPRODUCTION
PLAYPRODUCTION
†
;
(2 marks)
1 for Criteria
1 for correct Field &
Table & Sort & Show
& or
(1 mark)
Ascending/
Descending
;
;
Criteria:
>=6
or:
(1 mark)
(1 mark)
[5]
© UCLES 2016
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372
Cambridge International Examinations
Cambridge Ordinary Level
* 6 5 4 3 2 0 7 9 0 7 *
2210/23
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
October/November 2016
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 11 printed pages and 1 blank page.
DC (LK/SW) 125804/1
© UCLES 2016
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373
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release Material
The headteacher of a school needs a program to record and count the votes for a class captain.
Each student in the class will be allowed one vote. There can be up to 30 students in a class.
Write and test a program for the headteacher.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Set up the voting
Each class can choose from up to four different students as candidates for their class captain. Set
up a routine that allows:
•
•
•
•
•
between two and four different candidate names to be input and stored
the candidate names to be displayed with a number (1, 2, 3 or 4) beside each name
a choice of 1, 2, 3 or 4 to be entered to record a vote; all other entries are rejected
up to four totals set to zero ready to record the votes
a maximum of 30 votes to be cast
TASK 2 – Record and count each vote
Input a number 1, 2, 3 or 4; add 1 to the appropriate total.
Output the name of the candidate voted for or output ‘invalid vote’ if a vote is rejected.
TASK 3 – Show the result
When all the votes have been cast, display the candidates’ names with their totals in descending
order of totals. If there is a clear winner, display the candidate’s name with the words ‘NEW CLASS
CAPTAIN’ beside it; otherwise display ‘NO OVERALL WINNER’.
© UCLES 2016
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374
1
(a) All variables, constants and other identifiers should have meaningful names.
For four of the variables, constants or arrays that you used in Task 1, state the name, data
structure, data type and its use.
Name 1 ......................................................................................................................................
Data structure ............................................................................................................................
Data type ...................................................................................................................................
Use ............................................................................................................................................
Name 2 ......................................................................................................................................
Data structure ............................................................................................................................
Data type ...................................................................................................................................
Use ............................................................................................................................................
Name 3 ......................................................................................................................................
Data structure ............................................................................................................................
Data type ...................................................................................................................................
Use ............................................................................................................................................
Name 4 ......................................................................................................................................
Data structure ............................................................................................................................
Data type ...................................................................................................................................
Use ........................................................................................................................................[8]
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375
(b) Write an algorithm to complete Task 2, using either pseudocode, programming statements
or a flowchart. You can assume that Task 1 has been completed and that there are three
candidates for class captain.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
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376
(c) Explain how you show the result (Task 3). You may include programming statements as part
of your explanation.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[6]
(d) Explain how you could extend your solution to deal with the case of ‘NO OVERALL WINNER’.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
© UCLES 2016
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377
Section B
2
Read this section of program code that:
•
•
•
inputs 10 numbers
checks whether each number is within a specified range
totals the numbers within the range and outside the range
1
2
3
4
5
6
7
8
9
InRange = 0
OutRange = 1000
FOR Count = 1 TO 10
INPUT Num
IF Num > 10 AND Num < 20 THEN InRange = InRange + 1
ELSE OutRange = OutRange - 1
Count = Count + 1
NEXT X
PRINT InRange, OutRange
(a) There are four errors in this code.
Locate these errors and suggest a correction to remove each error.
Error 1 ........................................................................................................................................
Correction ..................................................................................................................................
...................................................................................................................................................
Error 2 ........................................................................................................................................
Correction ..................................................................................................................................
...................................................................................................................................................
Error 3 ........................................................................................................................................
Correction ..................................................................................................................................
...................................................................................................................................................
Error 4 ........................................................................................................................................
Correction ..................................................................................................................................
...............................................................................................................................................[4]
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(b) Decide, with reasons, whether the numbers 10 and 20 are within or outside the range.
Number
Within
range (✓)
Outside
range (✓)
Reason
10
……………………………………………………………………..
……………………………………………………………………..
20
……………………………………………………………………..
……………………………………………………………………..
[4]
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3
The flowchart below inputs the price of an item under $10. The change from a $10 note is output.
Any amount less than 5 cents is rounded up to 5 cents.
The predefined function INT rounds a number down to the nearest whole number; for example
Z ← INT(5.7) gives the value Z = 5
START
INPUT Price
Change
10 – Price
Is
Change
>= 1?
Yes
No
Dollars
Change
INT(Change)
Change – INT(Change)
OUTPUT Dollars,
" dollars"
Is
Change
>= 0.5?
Yes
Change
No
TenCents
Change – 0.5
OUTPUT "One 50
cent coin"
INT(Change * 10 + 0.5)
OUTPUT TenCents,
" ten cent coins"
Is Change*10 –
TenCents
> 0?
Yes
No
END
© UCLES 2016
2210/23/O/N/16
OUTPUT "One 5
cent coin"
.
9
380
Complete the trace table for the input data: 6.29
Price
Change
Dollars
TenCents
OUTPUT
[5]
4
Four validation checks and four descriptions are shown below.
Draw a line to link each validation check to the correct description.
Validation check
Description
Presence check
Numbers between two
given values are accepted
Range check
Data is of a particular
specified type
Type check
Data contains an exact
number of characters
Length check
Ensures that some data
have been entered
[3]
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81
5
REPEAT ... UNTIL
and
WHILE ... DO ... ENDWHILE are two different loop
structures you can use when writing pseudocode.
Explain, using examples, why you would choose to use each type of loop.
Example 1 .........................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Reason for choice .............................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Example 2 .........................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Reason for choice .............................................................................................................................
..........................................................................................................................................................
......................................................................................................................................................[6]
© UCLES 2016
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82
6
A database, THEATRETOURS, was set up to show the tour dates, towns, number of seats and
prices in local currency for a Shakespeare play.
Town
Tour Date
Number of Seats
Price Local Currency
Wigan
18/08/2016
120
15.00
Dumfries
20/08/2016
160
12.50
Turin
25/08/2016
200
17.00
Macon
27/08/2016
75
18.00
Bordeaux
29/08/2016
170
20.00
Algiers
01/09/2016
125
1350.00
Windhoek
05/09/2016
65
90.00
Windhoek
06/09/2016
65
90.00
Port Elizabeth
10/09/2016
200
110.00
(a) Explain why none of the fields in the database can be used as a primary key.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(b) State a field that could be added as a primary key.
...................................................................................................................................................
Give a reason for choosing this field.
...................................................................................................................................................
...............................................................................................................................................[2]
(c) Use the query-by-example grid below to provide a list of tour dates and seat prices in
alphabetical order of town.
Field:
Table:
Sort:
Show:
Criteria:
or:
[4]
© UCLES 2016
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383
Cambridge International Examinations
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/23
October/November 2016
Paper 2
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the October/November 2016 series for most
®
Cambridge IGCSE , Cambridge International A and AS Level components and some Cambridge O Level
components.
® IGCSE is the registered trademark of Cambridge International Examinations.
This document consists of 5 printed pages.
© UCLES 2016
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Mark Scheme
384
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
23
Section A
1
(a) Many correct answers, the identifiers must be meaningful. These are examples only.
There are two marks available for each identifier:
• 1 mark for suitable name
• 1 mark for a suitable data structure, data type and use
– MaxVotes, constant, integer, maximum number of votes that can be cast
– CandidateName, array, string, name of candidate
– NoCandidates, variable, integer, number of candidates
– TotalNoCandidateVotes, array, integer, total number of votes cast
[8]
(b) Any four from:
– prompt for input of candidate number
– input of candidate number
– check for candidate number of 1, 2 or 3
– output ‘invalid vote’ if input not 1, 2, or 3
– otherwise add 1 to appropriate total and …
– … output name of candidate voted for
[4]
(c) Description (may include reference to programming statements) any six marks from
– output total and …
– … corresponding candidate name...
– description of method for selecting descending order of totals
– evidence that the method works
– check if highest number of votes is a unique value
– if unique output the candidate name and ‘NEW CLASS CAPTAIN’
– otherwise output ‘NO OVERALL WINNER’
[6]
(d) Accept any reasonable suggestion(s), two marks can be awarded for either a suggestion with
an accompanying description e.g.
– re run the voting (1) without the least popular candidate (1)
or accept two different suggestions e.g.
– re run the voting
– give the teacher the casting vote.
© UCLES 2016
[2]
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Mark Scheme
385
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
23
Section B
2
(a) 1 mark for each change
– Line 2: OutRange = 0
– Line 6: should be OutRange = OutRange + 1
– Line 7: not needed
– Line 8: NEXT X should be NEXT Count / Line 3: FOR Count = 1 TO 10 should be
FOR X = 1 TO 10
[4]
(b)
Number
Within
range (9)
Outside
range (9)
Reason
10
9
Range greater than 10, so 10 not included
…………………………………………………………
20
9
Range less than 20, so 20 not included
…………………………………………………………
[4]
3
Price
Change
Dollars
TenCents
OUTPUT
6.29
3.71
3
0.71
3 dollars
0.21
One 50 cent coin
2
2 ten cent coins
One 5 cent coin
(1 mark per correct column)
[5]
© UCLES 2016
Page 4
4
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Mark Scheme
386
Cambridge O Level – October/November 2016
Syllabus
2210
Paper
23
1 mark for each correct link up to maximum of 3 marks
[3]
5
For each example 1 mark for correct structure, 1 mark for appropriate content inside loop and
1 mark for reason. There are many correct answers these are only samples
REPEAT
..INPUT Number
Total ← Total + Number
UNTIL Number = 0
– at least one repeat is required
6
WHILE Number <> -1 DO
..INPUT Number
Total ← Total + Number
ENDWHILE
– the loop may never be executed
[6]
(a) –
–
Town has duplicate entries/all fields can have duplicate entries
fields other than Town not suitable identifiers
[2]
(b) –
–
Performance number …
… uniquely identifies each performance
[2]
© UCLES 2016
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Mark Scheme
387
Cambridge O Level – October/November 2016
(c)
Field: Town
Table: THEATRETOURS
Syllabus
2210
Tour Date
Price Local
Currency
THEATRETOURS
THEATRETOURS
;
;
Paper
23
Sort: Ascending
Show:
;
†
Criteria:
or:
1 mark for each column + 1 mark for correct fields only
© UCLES 2016
[4]
.
388
Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
* 4 5 7 2 4 7 7 1 5 8 *
0478/12
COMPUTER SCIENCE
Paper 1 Theory
May/June 2017
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 12 printed pages.
DC (CW/JG) 134134/3
© UCLES 2017
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389
1
Name three different buses that are used in the fetch-execute cycle.
Bus 1 ������������������������������������������������������������������������������������������������������������������������������������������������
Bus 2 ������������������������������������������������������������������������������������������������������������������������������������������������
Bus 3 ������������������������������������������������������������������������������������������������������������������������������������������������
[3]
2
Give two examples of primary, secondary and off-line storage.
Primary
Example 1 ����������������������������������������������������������������������������������������������������������������������������������������
Example 2 ����������������������������������������������������������������������������������������������������������������������������������������
Secondary
Example 1 ����������������������������������������������������������������������������������������������������������������������������������������
Example 2 ����������������������������������������������������������������������������������������������������������������������������������������
Off-line
Example 1 ����������������������������������������������������������������������������������������������������������������������������������������
Example 2 ����������������������������������������������������������������������������������������������������������������������������������������
[6]
© UCLES 2017
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390
3
The diagram shows five output devices and five descriptions.
Draw a line between each output device and its description.
Output Device
Description
Inkjet printer
Flat panel display that uses the light modulating
properties of liquid crystals.
LCD screen
Flat panel display that uses an array of
light‑emitting diodes as pixels.
2D cutter
Droplets of ink are propelled onto paper.
LED screen
Electrically charged powdered ink is transferred
onto paper.
Laser printer
High powered laser that uses the x-y plane.
[4]
© UCLES 2017
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4
There are various methods used to detect errors that can occur during data transmission and
storage.
Describe each of the following error detection methods.
Parity check �������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
Check digit ���������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
Checksum ����������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
Automatic Repeat request (ARQ) ����������������������������������������������������������������������������������������������������
����������������������������������������������������������������������������������������������������������������������������������������������������������
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[8]
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(a) The denary number 57 is to be stored in two different computer registers.
Convert 57 from denary to binary and show your working.
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(b) Show the binary number from part (a) as it would be stored in the following registers.
Register 1
Register 2
[2]
(c) A binary number stored in a register can have many different uses, for example an address in
main memory.
Give two other uses for a binary number stored in a register.
Use 1 ����������������������������������������������������������������������������������������������������������������������������������������
Use 2 ����������������������������������������������������������������������������������������������������������������������������������������
[2]
(d) A register in a computer contains binary digits.
0
0
1
1
1
0
1
0
The contents of the register represent a binary integer.
Convert the binary integer to hexadecimal.
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Airline boarding passes can be read from a smartphone instead of a printout.
Back
Boarding Pass
A
TSA Pre
Passenger Webb / Alan
B 15
Boarding
Boarding
Position
Group
Flight 683
JFK – LAX
Date
Thursday, November 10, 2016
Departs 8.15 pm
Gate
C4
Time, gate and terminals may change - check monitors
Fly Rewards
Fly Rewards# 12345678
Conf# BC123D
Identify what type of barcode A is an example of. Explain how the data stored in this type of
barcode is read.
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7
Computer A is communicating with computer B.
(a) Draw an arrow or arrows to show simplex, duplex and half-duplex data transmission. The
direction of the data transmission must be fully labelled.
Simplex data transmission
Computer A
Computer B
Duplex data transmission
Computer A
Computer B
Half-duplex data transmission
Computer A
Computer B
[6]
(b) State a use for the following data transmission methods. The use must be different for each
data transmission method.
Simplex �������������������������������������������������������������������������������������������������������������������������������������
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Duplex ��������������������������������������������������������������������������������������������������������������������������������������
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[2]
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(c) A computer includes an Integrated Circuit (IC) and a Universal Serial Bus (USB) for data
transmission.
Describe how the computer uses these for data transmission, including the type of data
transmission used.
IC ����������������������������������������������������������������������������������������������������������������������������������������������
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USB ������������������������������������������������������������������������������������������������������������������������������������������
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[4]
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8
A company has a number of offices around the world.
(a) Data is transmitted between the offices over the Internet. In order to keep the data safe the
company is using Secure Socket Layer (SSL) protocol and a firewall at each office.
Explain how SSL protocol and a firewall will keep the company’s data safe.
SSL protocol �����������������������������������������������������������������������������������������������������������������������������
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Firewall �������������������������������������������������������������������������������������������������������������������������������������
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[4]
(b) A company stores personal details of its customers on a computer system behind a firewall.
Explain, with reasons, what else the company should do to keep this data safe.
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9
A cold store is kept at a constant low temperature using a sensor, a microprocessor and a cooling
unit.
Explain how the sensor and microprocessor will maintain a constant low temperature.
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98
10 For this logic statement:
X = 1 if (( A is 1 AND B is 1 ) OR ( B is 1 AND C is NOT 1 ))
(a) Draw the logic circuit.
A
B
X
C
[4]
(b) Complete the truth table for the given logic statement.
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Working space
X
[4]
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11
A company sells smartphones over the Internet.
Explain how the information stored on the company’s website is requested by the customer, sent
to the customer’s computer and displayed on the screen.
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Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
COMPUTER SCIENCE
0478/12
Paper 1
May/June 2017
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2017 series for most Cambridge IGCSE®,
Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level
components.
® IGCSE is a registered trademark.
This syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 9 printed pages.
© UCLES 2017
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Cambridge IGCSE – Mark Scheme
PUBLISHED
401
Question
1
Answer
•
•
•
2
Marks
3
address (bus)
control (bus)
data (bus)
Question
May/June 2017
Answer
2 marks for each type of storage
Marks
6
Primary storage
• RAM
• ROM
Secondary storage
• hard disk drive (HDD)
• solid state drive (SSD)
Off-line storage e.g.
• CD
• DVD
• Blu-ray
• Flash memory // USB storage
• removable / external / portable hard disk drive (HDD/SSD)
• SD card
Question
Answer
3
4
1 mark for each correct line to a max of 4 marks.
© UCLES 2017
Marks
Page 2 of 9
0478/12
Question
4
.
Cambridge IGCSE – Mark Scheme
PUBLISHED
402
May/June 2017
Answer
Two marks for each correct description
Parity Check
• Checks a byte of data
• Check is performed when data is received
• A parity bit is added (to the parity byte)
• Counts / checks number of 1’s // counts / checks to see if 1’s are even
// counts / checks to see if 1’s are odd
• Can be even or odd
• If parity is incorrect, error is detected
Check digit
• A digit that is calculated from the data // uses modulo to calculate digit
// valid description of modulo
• It is appended / added to the data
• Digit is recalculated when data is entered
• Digits are compared to check for error
Checksum
• A value is calculated from the data // Valid description of calculation
• It is transmitted with the data
• Value is recalculated after transmission
• Values are compared after transmission to check for error
Automatic Repeat reQuest
• Uses acknowledgement / request and time-out
• Error control protocol
• Check performed on receiving data // error is detected by e.g. parity
check, check sum
• If error detected, request is sent to resend data // negative
acknowledgement is used
• Resend request is repeated till data is sent correctly / requests time
out / limit is reached
• Send acknowledgement that data is received // positive
acknowledgement is used
• If acknowledgement not received in set time data is resent
© UCLES 2017
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Marks
8
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Question
5(a)
May/June 2017
Cambridge IGCSE – Mark Scheme
PUBLISHED
403
Answer
Marks
1 mark for correct method, 1 mark for correct answer
2
32 + 16 + 8 + 1
(00)111001
5(b)
registers must have leading zeros, allow follow through from 5(a) for an
incorrect value
1 mark for each correct register.
0
0
0
5(c)
0
0
0
1
0
0
0
0
0
0
1
0
1
1
1
0
0
data
ASCII value / Unicode value / character
number
part of image / small image
a sound / sound sample / small sound track
instruction
1
Answer
1 mark for correct name of code, up to a further 3 marks for appropriate
explanation
•
Quick response (QR) Code
Three from:
• Barcode is captured / scanned / imaged, by a camera / scanner /
barcode reader / QR code reader
• Read using a laser
• Processed by an app
• Light is reflected back
• Black squares reflect less light than white squares
• Modules are used for orientation / alignment
• Squares / data are decoded
© UCLES 2017
1
2
3A
Question
6
0
1
Two from:
•
•
•
•
•
•
5(d)
1
2
Page 4 of 9
Marks
4
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Cambridge IGCSE – Mark Scheme
PUBLISHED
404
Question
7(a)
May/June 2017
Answer
1 mark for correct arrow(s), one mark for correct description
OR
(Direction of data is) one way only // unidirectional
#
(Direction of data is both ways) at same time / simultaneously / concurrently
AND
(Direction of data is both ways) but at different times / not at the same time /
not simultaneously / not concurrently
© UCLES 2017
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Marks
6
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Cambridge IGCSE – Mark Scheme
PUBLISHED
405
Question
7(b)
May/June 2017
Answer
1 mark each use, must be different.
Marks
2
Simplex e.g.:
Microphone to computer
Sensor to computer
Computer to printer
Computer to speaker
Computer to monitor
Webcam to computer
Sending data to a device // sending data from a device
Duplex e.g.:
Telephone call
Voice over IP
Computer to printer (only award once)
Instant messaging
Broadband connections
Video conferencing
Sending data to and from devices e.g wireless technology
Computer to modem
7(c)
2 marks for IC, 2 marks for USB
4
IC
•
•
USB
•
•
Question
8(a)
parallel transmission // description of parallel
for sending data internally
serial transmission // description of serial
for sending data externally (to and from peripherals / between
devices)
Answer
2 marks for SSL, 2 marks for Firewall
SSL protocol
Two from:
• uses encryption
• encryption is asymmetric / symmetric / both
• makes use of (public and private) keys
• data is meaningless (without decryption key / if intercepted)
Firewall
Two from:
• helps prevent unauthorised access // helps prevent hacking
• checks that data meets criteria // identifies when data does not meet
criteria
• acts as a filter for (incoming and outgoing) data // blocks any
unacceptable data //allows acceptable data through
© UCLES 2017
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Marks
4
.
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Cambridge IGCSE – Mark Scheme
PUBLISHED
406
Question
8(b)
May/June 2017
Answer
Six from:
Marks
6
Encrypt the data «
« so it cannot be understood by those not entitled to view it
Password protected / biometrics «
« to help prevent unauthorised access
Virus checking software «
« helps prevent data corruption or deletion
« identifies / removes a virus in the system
« scans a system for viruses
Spyware checking software «
« helps prevent data being stolen/copied/logged
« scans a system for spyware
Drop-down input methods / selectable features «
« to reduce risk of spyware / keylogging
Physical method e.g. locked doors / CCTV timeout / auto log off
« to help prevent unauthorised access
Network / company policies // training employees
« to educate users how to be vigilant
Access rights «
« allows users access to data that they have permission to view
« prevents users from accessing data that they do not have permission to
view
Question
9
Answer
Six from:
•
•
•
•
•
•
•
•
•
•
© UCLES 2017
Marks
6
temperature sensor
analogue data / temperature is converted to digital data (with an ADC)
sensor sends signal to the microprocessor
microprocessor compares input values with stored values/pre-set
values «
« if the temperature value input is too high/low «
« a signal is sent from the microprocessor to turn on / off / up / down
the cooling unit
« if temperature matches the stored values «
« no action is taken
an actuator is used to turn the cooling unit on / off / up / down
the process is a continuous loop
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PUBLISHED
407
Question
10(a)
Answer
Marks
1 mark for each correct gate, with the correct input(s)
10(b)
4
4
A
B
C
X
0
0
0
0
0
0
1
0
0
1
0
1
0
1
1
0
1
0
0
0
1
0
1
0
1
1
0
1
1
1
1
1
4 marks for 8 correct outputs
3 marks for 6 or 7 correct outputs
2 marks for 4 or 5 correct outputs
1 mark for 2 or 3 correct outputs
© UCLES 2017
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PUBLISHED
408
Question
11
May/June 2017
Answer
Seven from:
7
Requested
• a web browser is used
• user enters the URL / web address (into the address bar) // clicks a
link containing the web address // clicks an element of the webpage
• the URL / web address specifies the protocol
• protocols used are Hyper Text Transfer Protocol (HTTP) / Hyper Text
Transfer Protocol Secure (HTTPS)
Sent
•
•
•
•
•
the URL / web address contains the domain name
the Internet Service Provider (ISP) looks up the IP address of the
company
the domain name is used to look up the IP address of the company
the domain name server (DNS) stores an index of domain names and
IP addresses
web browser sends a request to the web server / IP address
Received
• Data for the website is stored on the company’s web server
• webserver sends the data for the website back to the web browser
• web server uses the customer’s IP address to return the data
• the data is transferred into Hyper Text Mark-up Language (HTML)
• HTML is interpreted by the web browser (to display the website)
© UCLES 2017
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
0478/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2017
PRE-RELEASE MATERIAL
No Additional Materials are required.
* 9 6 0 8 7 9 8 3 5 0 *
This material should be given to the relevant teachers and candidates as soon as it has been received
at the Centre.
READ THESE INSTRUCTIONS FIRST
Candidates should use this material in preparation for the examination. Candidates should attempt the
practical programming tasks using their chosen high-level, procedural programming language.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 2 printed pages.
DC (RW) 132151/3
© UCLES 2017
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410
In preparation for the examination candidates should attempt the following practical tasks by writing
and testing a program or programs.
The organiser of a senior citizens’ club arranges outings for the members. For each of these outings a
coach is hired, meals at a restaurant are reserved and tickets for the theatre are booked. A program is
required to work out the costs and provide a printed list showing everyone on the outing.
Write and test a program for the club organiser.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Work out the total cost of the outing.
The organiser finds out how many senior citizens would be interested in the outing. The program for
TASK 1 works out the cost from this information.
Number of people
Hire of coach ($)
Cost of a meal ($)
Cost of a theatre ticket ($)
12–16
150
14.00
21.00
17–26
190
13.50
20.00
27–39
225
13.00
19.00
The minimum number of senior citizens needed for the outing to go ahead is 10; there cannot be more
than 36 senior citizens on the outing. A minimum of two carers must go on the outing, with an additional
carer needed if more than 24 senior citizens go on the outing. Carers do not have to pay anything for
the outing. Work out the total cost and the cost per person for the senior citizens.
TASK 2 – Record who is going on the outing and how much has been paid.
Using your results from TASK 1, record the names of the people on the outing and the amount they
have paid; include the carers on the outing. If there are spare places on the coach then extra people
can be added; they are charged the same price as the other senior citizens. Calculate the total amount
of money collected. Print out a list of the people on the outing.
TASK 3 – Identify the break-even point or profit that will be made on the outing.
Show whether the outing has made a profit or has broken even using the estimated cost from TASK 1
and the money collected from TASK 2.
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2017
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Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
* 5 4 1 6 1 0 3 0 3 1 *
0478/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2017
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
The syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 11 printed pages and 1 blank page.
DC (RW/CGW) 132150/3
© UCLES 2017
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412
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release material
The organiser of a senior citizens’ club arranges outings for the members. For each of these
outings a coach is hired, meals at a restaurant are reserved and tickets for the theatre are booked.
A program is required to work out the costs and provide a printed list showing everyone on the outing.
Write and test a program for the club organiser.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Work out the total cost of the outing.
The organiser finds out how many senior citizens would be interested in the outing. The program for
TASK 1 works out the cost from this information.
Number of people
Hire of coach ($)
Cost of a meal ($)
Cost of a theatre ticket ($)
12–16
150
14.00
21.00
17–26
190
13.50
20.00
27–39
225
13.00
19.00
The minimum number of senior citizens needed for the outing to go ahead is 10; there cannot be
more than 36 senior citizens on the outing. A minimum of two carers must go on the outing, with an
additional carer needed if more than 24 senior citizens go on the outing. Carers do not have to pay
anything for the outing. Work out the total cost and the cost per person for the senior citizens.
TASK 2 – Record who is going on the outing and how much has been paid.
Using your results from TASK 1, record the names of the people on the outing and the amount they
have paid; include the carers on the outing. If there are spare places on the coach then extra people
can be added; they are charged the same price as other senior citizens. Calculate the total amount
of money collected. Print out a list of the people on the outing.
TASK 3 – Identify the break-even point or profit that will be made on the outing.
Show whether the outing has made a profit or has broken even using the estimated cost from TASK 1
and the money collected from TASK 2.
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413
1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
For a variable that you have used to record information about the cost of the outing in
Task 1, state the name, data type and its use.
Variable name ....................................................................................................................
Data type ............................................................................................................................
Use .....................................................................................................................................
[3]
(ii)
State two constants that you could have used for Task 1. Give the value that would be
assigned to each one and explain what it is used for.
Constant 1 name ................................................................................................................
Value 1 ...............................................................................................................................
Use 1 ..................................................................................................................................
Constant 2 name ................................................................................................................
Value 2 ...............................................................................................................................
Use 2 ..................................................................................................................................
[6]
(b) Explain how you would need to change your calculation in Task 1 if each carer were paid
$20.00 for coming on the outing.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
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(c) Write an algorithm to complete Task 2, using either pseudocode, programming statements
or a flowchart. You can assume that Task 1 has been completed. You do not need to produce
the list of people on the outing.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
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415
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
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(d) Explain how your program completes Task 3. Any programming statements used in your
answer must be fully explained.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
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Section B
2
(a) Write an algorithm to input three different numbers, and then output the largest number. Use
either pseudocode or a flowchart.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
(b) Give two sets of test data to use with your algorithm in part (a) and explain why you chose
each set.
Test data set 1 ...........................................................................................................................
Reason ......................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Test data set 2 ...........................................................................................................................
Reason ......................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[4]
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3
This flowchart inputs the weight of items in kilograms to be loaded on a trailer. Any item over
25 kilograms is rejected. The trailer can take up to 100 kilograms.
START
TotalWeight
0
Reject
0
INPUT Weight
Yes
Is Weight
˃ 25?
Reject
No
TotalWeight
TotalWeight + Weight
Is
TotalWeight
˃ 100?
No
Yes
TotalWeight
TotalWeight – Weight
OUTPUT 'Weight of items '’
TotalWeight, ' Number of
items rejected ',Reject
END
© UCLES 2017
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Reject + 1
.
9
419
Complete the trace table for the input data:
13, 17, 26, 25, 5, 10, 15, 35, 20, 15
Weight
Reject
TotalWeight
OUTPUT
[5]
© UCLES 2017
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20
4
An algorithm has been written in pseudocode to input 100 numbers and print out the sum.
A REPEAT … UNTIL loop has been used.
Count ← 0
Sum ← 0
REPEAT
INPUT Number
Sum ← Sum + Number
Count ← Count + 1
UNTIL Count > 100
PRINT Sum
(a) Find the error in the pseudocode and suggest a correction.
Error ...........................................................................................................................................
Correction .................................................................................................................................
...................................................................................................................................................
[2]
(b) Rewrite the correct algorithm using a more suitable loop structure.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
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21
5
A database table, SHEEP, is used to keep a record of the sheep on a farm. Each sheep has a
unique ear tag, EARnnnn; n is a single digit. The farmer keeps a record of the date of birth, the
gender and the current weight of each sheep in kilograms.
(a) Identify the four fields required for the database. Give each field a suitable name and data
type. Provide a sample of data that you could expect to see in the field.
Field 1 name ..............................................................................................................................
Data type ...................................................................................................................................
Data sample ..............................................................................................................................
Field 2 name ..............................................................................................................................
Data type ...................................................................................................................................
Data sample ..............................................................................................................................
Field 3 name ..............................................................................................................................
Data type ...................................................................................................................................
Data sample ..............................................................................................................................
Field 4 name ..............................................................................................................................
Data type ...................................................................................................................................
Data sample ..............................................................................................................................
[8]
(b) State the field that you would choose as the primary key.
...............................................................................................................................................[1]
(c) Using the query-by-example grid below, write a query to identify the ear tags of all male
sheep weighing over 10 kilograms. Only display the ear tags.
Field:
Table:
Sort:
Show:
Criteria:
or:
[3]
© UCLES 2017
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422
Cambridge International Examinations
Cambridge International General Certificate of Secondary Education
COMPUTER SCIENCE
0478/22
Paper 2
May/June 2017
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge will not enter into discussions about these mark schemes.
Cambridge is publishing the mark schemes for the May/June 2017 series for most Cambridge IGCSE®,
Cambridge International A and AS Level and Cambridge Pre-U components, and some Cambridge O Level
components.
® IGCSE is a registered trademark.
This syllabus is approved for use in England, Wales and Northern Ireland as a Cambridge International Level 1/Level 2 Certificate.
This document consists of 6 printed pages.
© UCLES 2017
[Turn over
.
0478/22
Question
1(a)(i)
May/June 2017
Cambridge IGCSE – Mark Scheme
PUBLISHED
423
Answer
One variable name MUST relate to the cost of the outing in Task 1
Variable name
Data type to match variable
Description of the use of the given variable
Marks
3
(1)
(1)
(1)
Many correct answers, they must be meaningful. This is an example only.
NoSeniorCitizens (1), integer (1), number of senior citizens that
want to go on the outing (1)
1(a)(ii)
Two constants required, for each constant
Name
Value
Use
6
(1)
(1)
(1)
Many correct answers, they must be meaningful. These are examples only.
MinNoSeniorCitizens (1), 10 (1), minimum number of senior
citizens that can go on the outing (1)
MaxNoSeniorCitizens (1), 36 (1), maximum number of senior
citizens that can go on the outing (1)
Max 6 marks
1(b)
-
© UCLES 2017
calculate cost of carers // if more than 24 senior citizens on the trip cost
is 60 otherwise cost is 40
add to the cost of the outing
Page 2 of 6
2
0478/22
Question
1(c)
.
Cambridge IGCSE – Mark Scheme
PUBLISHED
424
May/June 2017
Answer
Any five from:
loop for number of senior citizens on the trip
input with prompts name and amount paid
store name and amount paid in appropriate place in arrays
total the amount paid
check if spare places are available
if spare place is required remove a spare place//fill spare places
add name(s) to list in appropriate place(s)
store names of two carers
If number of senior citizens > 24 store name of third carer
Max 5 marks
Marks
5
Example
TotalPaid
0
FOR Counter
1 TO NoSenCit
PRINT "Please Enter Name"
INPUT SenCitName[Counter]
PRINT "Please Enter amount paid"
INPUT SenCitAmount[Counter]
TotalPaid
TotalPaid + Amount
NEXT Counter
Extras
TRUE
WHILE NoSenCit < 36 and Extras
PRINT "Do you want to add another person? Y/N"
INPUT Answer
IF Answer = "Y"
THEN
NoSenCit
NoSenCit + 1
PRINT "Please Enter Name"
INPUT SenCitName[NoSenCit]
ELSE Extras
FALSE
ENDIF
ENDWHILE
PRINT "Please Enter Name of First Carer"
INPUT Carer1
PRINT "Please Enter Name of Second Carer"
INPUT Carer2
IF NoSenCit > 24
THEN
PRINT "Please Enter Name of Third Carer"
INPUT Carer3
ENDIF
1(d)
© UCLES 2017
Explanation (any programming statements must be fully explained)
check total cost
««against total amount paid
if total cost < total amount paid display/show profit
if total cost = total amount paid display/show break even
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Question
2(a)
May/June 2017
Cambridge IGCSE – Mark Scheme
PUBLISHED
425
Answer
Marks
award full marks for any working solution
Input three numbers
Attempt to select largest number
Working method
print out largest number
4
(1)
(1)
(1)
(1)
Sample algorithm
INPUT Num1, Num2, Num3
IF (Num1 > Num2) AND (Num1 > Num3) THEN PRINT Num1
ENDIF
IF (Num2 > Num1) AND (Num2 > Num3) THEN PRINT Num2
ENDIF
IF (Num3 > Num1) AND (Num3 > Num2) THEN PRINT Num3
ENDIF
or
INPUT Num1
Big
Num1
INPUT Num2, Num3
IF Num2 > Big THEN Big
IF Num3 > Big THEN Big
PRINT Big
2(b)
Num2 ENDIF
Num3 ENDIF
1 mark for each data set and 1 mark for the matching reason.
4
There are many possible correct answers, these are examples only.
Test data set 1:
Reason:
30, 29, 28
first number is the largest
Test data set 2:
Reason:
x, y, z
abnormal data, should be rejected
Max 4 marks
© UCLES 2017
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Question
Answer
3
Weight
Reject
Total Weight
0
0
13
13
17
30
26
55
5
60
10
70
15
85
OUTPUT
105
(1 mark)
85
Weight of items 85 Number of
items rejected 2
(1 mark to 1st
85)
(1 mark 105, 85)
(1 mark)
Question
Answer
Error
Correction
or
Error
Correction
or
5
2
20
( 1mark)
Marks
1
25
35
4(a)
May/June 2017
Cambridge IGCSE – Mark Scheme
PUBLISHED
426
- Count
- Count
0
1
Marks
2
- UNTIL Count > 100
- UNTIL Count >= 100 or UNTIL Count = 100
UNTIL Count > 99
4(b)
-
use of FOR with correct start and end values «
« use of NEXT
« removal of increment for Count
3
Sample algorithm
Sum
0
FOR Count
1 TO 100
INPUT Number
Sum
Sum + Number
NEXT // NEXT Count
PRINT Sum
5(a)
for each field name (1), data type and sample (1)
The following are examples there are many different correct answers.
EarTag (1), text, EAR1011 (1)
DOB (1), date, 4/3/2017 (1)
Gender (1), text, M (1)
Weight (1), number, 5.9 (1)
© UCLES 2017
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Question
5(b)
5(c)
May/June 2017
Cambridge IGCSE – Mark Scheme
PUBLISHED
427
Answer
Marks
EarTag
Field:
1
EarTag
Table: SHEEP
Gender
SHEEP
3
Weight
SHEEP
Sort:
Show:
;
Criteria:
†
=’M’
†
> 10
or:
(1 mark)
© UCLES 2017
(1 mark)
Page 6 of 6
(1 mark)
†
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428
Cambridge International Examinations
Cambridge Ordinary Level
* 1 2 0 2 9 2 7 4 5 6 *
2210/12
COMPUTER SCIENCE
Paper 1 Theory
October/November 2017
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name on all the work you hand in.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 12 printed pages.
DC (SC) 152928
© UCLES 2017
[Turn over
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429
1
A robot arm in a factory is programmed to move products.
The binary instructions to operate the robot arm are:
Operation
Binary Instruction
UP
1
1
1
1
DOWN
0
0
0
1
LEFT
1
0
0
1
RIGHT
0
1
1
0
OPEN
1
1
0
0
CLOSE
0
0
1
1
The instructions are entered as hexadecimal values.
An operator enters the values:
9
1
C
3
F
Convert the values and write down the operation (e.g. RIGHT) carried out by the robot arm.
9
.............................................................................
1
.............................................................................
C
.............................................................................
3
.............................................................................
F
.............................................................................
[5]
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2
Storage devices and storage media can be categorised as primary, secondary or off-line.
Write primary, secondary or off-line next to each storage device or medium to indicate its most
suitable category.
3
HDD
....................................................................................................................................
RAM
....................................................................................................................................
ROM
....................................................................................................................................
CD-ROM
....................................................................................................................................
SSD
....................................................................................................................................
DVD-RAM
....................................................................................................................................
[6]
(a) Explain the differences between the binary number system and the denary number system.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
(b) Explain the process of converting the binary number 1010 into a denary number.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
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4
A file server is used as a central data store for a network of computers.
Rory sends data from his computer to a file server that is approximately 100 metres away.
It is important that the data is transmitted accurately. Rory needs to be able to read data from and
write data to the file server at the same time.
(a) (i)
Use ticks (3) to identify the most suitable data transmission methods for this application.
Method 1
Tick
(3)
Method 2
Serial
Simplex
Parallel
Half-duplex
Tick
(3)
Duplex
[2]
(ii)
Explain why your answer to part (a)(i) is the most suitable data transmission.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[4]
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432
(b) Identify and describe two methods of error checking that can be used to make sure that the
data stored after transmission is accurate.
Method 1 ...................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Method 2 ...................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[6]
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5
Raj is using the Internet to do some online shopping. He visits a website that tells him that it uses
cookies.
(a) Explain what is meant by the term cookies.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
(b) Give two examples of the use of cookies.
Example 1 .................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Example 2 .................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
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6
Selma writes the following four answers in her Computer Science examination.
State which computer terms she is describing.
“It is a signal. When the signal is received it tells the operating system that an event has occurred.”
Selma is describing ..........................................................................................................................
“It takes source code written in a high level language and translates it into machine code. It
translates the whole of the source code at once.”
Selma is describing ..........................................................................................................................
“The part of the central processing unit (CPU) that carries out calculations.”
Selma is describing ..........................................................................................................................
“When data is transmitted, if an error is detected in the data received a signal is sent to ask for the
data to be retransmitted. This continues until the data received is correct.”
Selma is describing ..........................................................................................................................
[4]
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7
Draw a logic circuit to represent the logic statement:
X = 1 if (A is NOT 1 AND B is 1) AND (A is NOT 1 AND C is NOT 1) OR (B is 1 AND C is 1)
A
X
B
C
[7]
© UCLES 2017
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8
(a) A computer has 2048 MB of RAM.
How many GB of RAM does the computer have?
Show your working.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
..............................GB
[2]
(b) Describe one item that is stored in RAM.
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(c) Explain three ways that RAM is different to ROM.
1 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
2 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
3 ................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
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37
9
Anna has a farm that grows fruit.
She has a system that monitors the conditions for growing the fruit.
Sensors are used in this system.
(a) Explain what is meant by the term sensor.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(b) State two sensors that could be used in this system and describe how they could be used.
Sensor 1 ...................................................................................................................................
Use ...........................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Sensor 2 ...................................................................................................................................
Use ...........................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[6]
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38
10 (a) Describe what is meant by Transport Layer Security (TLS).
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
(b) Name three different applications of TLS.
1 ................................................................................................................................................
2 ................................................................................................................................................
3 ................................................................................................................................................
[3]
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39
11
Complete the paragraphs choosing the correct five terms from the list. Each term can only be
used once:
•
Ethics
•
Freeware
•
Free Software
•
Hacking
•
Malware
•
Plagiarism
•
Shareware
•
Virus
Taking another person’s work from the Internet and claiming it as your own is called
............................................. . It is possible to protect your work online with copyright.
One product that people may want to protect is software. ............................................. does allow
a person to share, copy and change software freely, but ............................................. does not
allow a person to do this legally. Software that has a licence allowing free use for a trial period
is called ............................................ . The name given to this area of Computer Science is
............................................. .
[5]
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2017
2210/12/O/N/17
.
440
Cambridge Assessment International Education
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/12
Paper 1
October/November 2017
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the October/November 2017 series for most
®
Cambridge IGCSE , Cambridge International A and AS Level components and some Cambridge O Level
components.
® IGCSE is a registered trademark.
This document consists of 9 printed pages.
© UCLES 2017
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Cambridge O Level – Mark Scheme
PUBLISHED
441
Question
1
Answer
1 mark per correct instruction:
October/November
2017
Marks
5
9 – LEFT
1 – DOWN
C – OPEN
3 – CLOSE
F – UP
Question
2
Answer
1 mark for each correct category:
Marks
6
HDD – Secondary
RAM – Primary
ROM – Primary
CD-ROM – Off-line
SSD – Secondary
DVD-RAM – Off-line
Question
3(a)
© UCLES 2017
Answer
Any four from (Max 2 per number system) :
Marks
4
•
•
A binary number system is a base-2 system
A denary number system is a base-10 system
•
•
A binary number system uses 0 and 1 values
A denary number system uses 0 to 9 values
•
•
A binary number system has units/ placeholders/column headings that increase by the power of 2
A denary number system has units/ placeholders/column headings that increase by the power of 10
•
Binary has more digit for the same value// Denary has less digits for the same value
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442
Question
3(b)
Answer
Five from:
• Correct column headings / place holders by example
• Correctly place a 1 or a 0 for each column
• Identify the columns to be added
• Add together the (denary) values identified «
• « this will give a total which is the denary number/answer
• Answer is 10
Question
Answer
4(a)(i)
Method 1
Serial
Parallel
Tick (9)
9
Method 2
© UCLES 2017
5
Marks
2
Tick (9)
Half-duplex
9
Any four from (Max 3 for serial):
• Serial has less/lower interference
• Serial is (more) reliable/accurate over distances
• In serial the bits won’t be skewed
• In serial it is easier to collate the bits together again after transmission
•
•
Marks
Simplex
Duplex
4(a)(ii)
October/November
2017
Duplex transmits data in both directions at the same time
simplex/half-duplex/remaining methods won’t allow read and write at same time
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443
Question
4(b)
October/November
2017
Answer
1 mark for error checking method, 2 marks for description:
Checksum
• A value is calculated from the data // Description of calculation
• Value is transmitted with data
• Value is recalculated after transmission
• If the values match the data is (more likely to be) accurate
Parity check
• A parity bit is transmitted with each byte of data
• Odd or even (parity can be used)
• Counts / checks number of 1’s // counts / checks to see if 1’s are even // counts / checks to see if 1’s are odd
• (Each byte is) checked after transmission to see if it matches the odd/even parity used
Automatic Repeat Request (ARQ)
• Uses acknowledgement and timeout
• When a device detects an error in data transmission it asks for the packet to be resent / no error detected, positive
acknowledgment sent
• The sending device resends the packet after the request to resend/ timeout received
• This process is continuous until the packet received is correct/until the ARQ limit is reached
Echo (check)
• Copy of data is sent back to sender
• Data is compared to see if it matches
• If it does not match error detected
© UCLES 2017
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Marks
6
.
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Cambridge O Level – Mark Scheme
PUBLISHED
444
Question
Answer
October/November
2017
Marks
5(a)
Any four from:
• Data / files
• Stored in a text file
• Downloaded to a user’s computer when a website is visited // webserver sends to web browser
• Stored on a user’s computer
• Stored by a browser
• Detected by the website when it is visited again
4
5(b)
Any two from: e.g.
• To store personal information/data
• To store login details
• To save items in an online shopping basket
• To track/save internet surfing habits // to track website traffic
• To carry out targeted advertising
• To store payment details
• To customise a webpage // to store user preferences
• Store progress in online games/quizzes
2
Question
6
© UCLES 2017
Answer
1 mark for each correct term, in this order:
• Interrupt
• Compiler
• ALU/Arithmetic and Logic Unit
• ARQ/Automatic repeat request
Marks
4
Page 5 of 9
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Question
7
© UCLES 2017
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PUBLISHED
445
Answer
1 mark for each correct logic gate with the correct input(s)
Page 6 of 9
October/November
2017
Marks
7
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
446
Question
8(a)
8(b)
8(c)
© UCLES 2017
October/November
2017
Answer
1 mark for correct calculation method, 1 mark for correct answer:
•
•
2048/1024 (or 1024 × 2)
2 GB
•
•
Instructions/programs/data
« currently in use
Marks
2
2
Any three from:
• RAM is volatile, ROM is non-volatile
• RAM is temporary, ROM is (semi) permanent
• RAM normally has a larger capacity than ROM
• RAM can be edited ROM cannot be edited // Data can be read from and written to RAM, ROM can only be read from.
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PUBLISHED
447
Question
9(a)
9(b)
Answer
•
•
It is an input device
It measures/takes (physical) readings of the surrounding environment / environment by example / physical properties
1 mark for each sensor, 2 marks for each description:
Marks
2
6
Moisture (sensor)
• To measure the water content of the soil
• To alert when the soil is too dry or too wet/needs watering
pH (sensor)
• To measure how acidic/alkaline the soil is
• To alert when there may be something polluting the soil
Light (sensor)
• To measure the brightness of the environment
• To alert when the fruit has too little/too much light
Temperature (sensor)
• To measure the temperature of the environment
• To alert when it is too hot/too cold for the fruit to grow
Gas (sensor)
• To measure the amount of CO2/oxygen present
• To alert when too much CO2/oxygen present
Humidity (sensor)
• To measure the water content in the air
• To alert when the air is too dry
Infra-red / motion (sensor)
• To measure level of infra-red/microwaves deflected
• To alert to any intruders e.g. animals stealing the fruit
© UCLES 2017
October/November
2017
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PUBLISHED
448
Question
Answer
October/November
2017
Marks
10(a)
Any three from:
• It is a (security) protocol
• It encrypts data (sent over the web/network)
• It is the updated version of SSL
• It has two layers
• It has a handshake layer
• It has a record layer
3
10(b)
1 mark for each correct application, examples could include:
• Online banking
• Online shopping // Online payment systems
• Email
• Cloud based storage
• Intranet/extranet
• VPN
• VoIP
• Instant messaging (IM) // social networking
3
Question
11
Answer
1 mark for each correct missing word, in the correct order:
•
•
•
•
•
© UCLES 2017
Plagiarism
Free software
Freeware
Shareware
Ethics
Page 9 of 9
Marks
5
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Cambridge International Examinations
Cambridge Ordinary Level
2210/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
October/November 2017
PRE-RELEASE MATERIAL
No Additional Materials are required.
* 2 0 1 9 5 2 0 9 7 9 *
This material should be given to the relevant teachers and candidates as soon as it has been received
at the Centre.
READ THESE INSTRUCTIONS FIRST
Candidates should use this material in preparation for the examination. Candidates should attempt the
practical programming tasks using their chosen high-level, procedural programming language.
This document consists of 2 printed pages.
DC (LK) 150364
© UCLES 2017
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In preparation for the examination candidates should attempt the following practical tasks by writing
and testing a program or programs.
The owner of a river boat hire company wants to calculate the daily profits from hiring out 10 rowing
boats on the river. Boats are numbered 1 to 10. Boats can be hired for use between 10:00 and 17:00
every day.
Write and test a program for the owner.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly and understandably.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – calculate the money taken in a day for one boat.
The cost of hiring a boat is $20 for one hour or $12 for half an hour. When a boat is hired the payment
is added to the money taken for the day. The running total of hours hired that day is updated and the
time when the boat must be returned is stored. At the end of the day the money taken and the total
hours hired is output.
No boat can be hired before 10:00 or returned after 17:00.
TASK 2 – find the next boat available.
Extend TASK 1 to work for all 10 rowing boats. Use the data stored for each boat to find out how many
boats are available for hire at the current time. If no boats are available show the earliest time that a
boat will be available for hire.
TASK 3 – calculate the money taken for all the boats at the end of the day.
At the end of the day use the data stored for each boat to calculate the total amount of money taken
and the total number of hours boats were hired that day. Find out how many boats were not used that
day and which boat was used the most. Provide a report for the owner to show this information.
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
© UCLES 2017
2210/22/PRE/O/N/17
.
451
Cambridge International Examinations
Cambridge Ordinary Level
* 7 5 7 6 9 3 0 3 8 4 *
2210/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
October/November 2017
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 10 printed pages and 2 blank pages.
DC (LK) 150363
© UCLES 2017
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452
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release material
The owner of a river boat hire company wants to calculate the daily profits from hiring out 10 rowing
boats on the river. Boats are numbered 1 to 10. Boats can be hired for use between 10:00 and 17:00
every day.
Write and test a program for the owner.
•
•
•
Your program must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly and understandably.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – calculate the money taken in a day for one boat.
The cost of hiring a boat is $20 for one hour or $12 for half an hour. When a boat is hired the payment
is added to the money taken for the day. The running total of hours hired that day is updated and the
time when the boat must be returned is stored. At the end of the day the money taken and the total
hours hired is output.
No boat can be hired before 10:00 or returned after 17:00.
TASK 2 – find the next boat available.
Extend TASK 1 to work for all 10 rowing boats. Use the data stored for each boat to find out how
many boats are available for hire at the current time. If no boats are available show the earliest time
that a boat will be available for hire.
TASK 3 – calculate the money taken for all the boats at the end of the day.
At the end of the day use the data stored for each boat to calculate the total amount of money taken
and the total number of hours boats were hired that day. Find out how many boats were not used
that day and which boat was used the most. Provide a report for the owner to show this information.
© UCLES 2017
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453
1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
For one variable that you have used to record the information about a single boat in
Task 1, state the name, data type and its use.
Variable name ...................................................................................................................
Data type ...........................................................................................................................
Use ....................................................................................................................................
[3]
(ii)
State one constant and its value that you could have used for Task 1.
Constant name ..................................................................................................................
Value .................................................................................................................................
[2]
(b) Give two different validation checks you could have used for data entry in Task 1. For each
check explain why it could be used and provide a set of data for testing.
Validation check 1 .....................................................................................................................
...................................................................................................................................................
Reason for choice .....................................................................................................................
...................................................................................................................................................
Set of test data .........................................................................................................................
...................................................................................................................................................
Validation check 2 .....................................................................................................................
...................................................................................................................................................
Reason for choice .....................................................................................................................
...................................................................................................................................................
Set of test data .........................................................................................................................
...................................................................................................................................................
[6]
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(c) Write an algorithm to complete Task 3, using either pseudocode, programming statements
or a flowchart. You may assume Task 2 has been completed.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
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455
(d) Explain how your program finds out how many boats are available for hire (Task 2).
Any programming statements used must be fully explained.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
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456
Section B
2
Write an algorithm using either pseudocode or a flowchart, to:
•
•
•
•
input a positive integer
use this value to set up how many other numbers are to be input
input these numbers
calculate and output the total and the average of these numbers.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
......................................................................................................................................................[6]
© UCLES 2017
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457
3
The following diagram shows four data structures and four descriptions.
Draw a line to connect each data structure to the correct description.
Data structure
Description
Constant
A collection of related data
Array
A value that can change whilst a
program is running
Table
A value that never changes whilst a
program is running
Variable
A series of elements of the same
data type
[3]
4
IF … THEN … ELSE … ENDIF is one type of conditional statement used when writing
pseudocode.
Identify and describe another type of conditional statement that you could use when writing
pseudocode. Give a reason why you would use this type of conditional statement.
Conditional statement ......................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Description .......................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
Reason .............................................................................................................................................
..........................................................................................................................................................
[4]
© UCLES 2017
2210/22/O/N/17
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458
5
(a) This flowchart checks a batch of 10 rice sacks for weight. Sacks should weigh 50 kilograms
each. Sacks weighing over 50.5 kilograms or less than 49.5 kilograms are rejected. The
number of sacks accepted and the number of sacks rejected is output.
START
0
0
0
Accept
Reject
Count
Is Count
= 10?
Accept
Accept + 1
Yes
OUTPUT
Accept,
Reject
No
Count
Count + 1
END
INPUT
Sack
Is Sack
< 49.5?
Yes
No
No
© UCLES 2017
Is Sack
> 50.5?
Yes
2210/22/O/N/17
Reject
Reject + 1
.
9
459
Complete the trace table for the input data:
50.4, 50.3, 49.1, 50.3, 50.0, 49.5, 50.2, 50.3, 50.5, 50.6
Accept
Reject
Count
Sack
OUTPUT
[5]
(b) The size of the batch has increased to 50 sacks. It has been decided to only reject sacks that
are underweight.
State the changes that need to be made to the flowchart.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
© UCLES 2017
2210/22/O/N/17
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60
6
A database table, TRAIN, is to be set up for a railway company to keep a record of the engines
available for use. Each engine has a unique number made up of 5 digits, nnnnn. The engines
are classified as freight (F) or passenger (P) together with a power classification that is a whole
number between 0 and 9, for example F8. The railway company keeps a record of the date of the
last service for each engine.
(a) Identify the three fields required for the database. Give each field a suitable name and data
type. Provide a sample of data that you could expect to see in the field.
Field 1 Name ............................................................................................................................
Data type ..................................................................................................................................
Data sample .............................................................................................................................
Field 2 Name ............................................................................................................................
Data type ..................................................................................................................................
Data sample .............................................................................................................................
Field 3 Name ............................................................................................................................
Data type ..................................................................................................................................
Data sample .........................................................................................................................[6]
(b) State the field that you should choose as the primary key.
...............................................................................................................................................[1]
(c) Using the query-by-example grid below, write a query to identify all passenger engines that
have not been serviced in the past 12 months. Only display the engine numbers.
Field:
Table:
Sort:
Show:
Criteria:
or:
[3]
© UCLES 2017
2210/22/O/N/17
.
461
Cambridge Assessment International Education
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/22
Paper 2
October/November 2017
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the October/November 2017 series for most
®
Cambridge IGCSE , Cambridge International A and AS Level components and some Cambridge O Level
components.
® IGCSE is a registered trademark.
This document consists of 8 printed pages.
© UCLES 2017
[Turn over
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
462
Question
1(a)(i)
Answer
1 mark for appropriate variable name, 1 mark for appropriate data type, 1 mark for appropriate use.
October/November
2017
Marks
3
Many correct answers, they must be meaningful. These are examples only.
– HireTotal, integer, running total of money taken (for the day)
– HoursHired, real, running total of hours hired for the day
– Returned, real, hour and fraction of hour when next returned
1(a)(ii)
1 mark for appropriate constant name, 1 mark for appropriate value.
2
Many correct answers, they must be meaningful. These are examples only.
– HourPrice, 20.00
– HalfHourPrice 12.00
1(b)
1 mark for validation check, all checks must be different, 1 mark for the reason and 1 mark for the test data.
The only inputs for task 1 can be length of hire, money taken, time of hire and time of return.
There are many possible correct answers these are examples only.
Validation check
Reason
Test data
Validation check
Reason
Test data
© UCLES 2017
– range check for time of hire
– cannot be hired before 10:00 returned after 17:00
– 12:00, 19:00
– type check for money taken
– must be a numeric value
– 20.00, bob
Page 2 of 8
6
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2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
463
Question
1(c)
October/November
2017
Answer
–
any loop for 10 boats
Marks
(1 mark)
Four from:
– Initialisation
– check HoursHired against MaxHoursHired «
« store the BoatNumber
« update MaxHoursHired if greater
– check if HoursHired = 0 …
… if so add 1 to NumberBoatsUnused
– update daily totals (for hours and money)
– output report with messages (including totals for hours and money, and number of boats unused and the most used
boat).
Max 4 marks
Example:
MaxHoursHired Å 0
TotalHoursHired Å 0
TotalMoney Å 0
NumberBoatsUnused Å 0
FOR BoatNumber Å 1 to 10
TotalMoney Å TotalMoney + Money(BoatNumber)
TotalHoursHired Å TotalHoursHired + HoursHired(BoatNumber)
IF HoursHired(BoatNumber) = 0
THEN NumberBoatsUnused Å NumberBoatsUnused + 1
ENDIF
IF HoursHired(BoatNumber) > MaxHoursHired
THEN
MostUsed Å BoatNumber
MaxHoursHired Å HoursHired(BoatNumber)
ENDIF
NEXT BoatNumber
PRINT "Boats were hired for ", TotalHoursHired, " hours"
PRINT "Total amount of money taken was ", TotalMoney
PRINT NumberBoatsUnused, " boats were not used"
Print "Boat number ", MostUsed, " was used most"
© UCLES 2017
Page 3 of 8
5
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
464
Question
1(d)
October/November
2017
Answer
Maximum 4 marks in total for question part
4
e.g.
Explanation (may include reference to program statements)
– check all boats for«
– « return time < current time // current booking slot available or return time > current time// current booking slot not
available
– keep a running total of those available
– display number of boats
Example:
FOR BoatNumber Å 1 to 10
loop to check for all boats
IF ReturnTime(BoatNumber) <= CurrentTime check return time against current time
THEN BoatsAvailable Å BoatsAvailable + 1
keep a running total
ENDIF
NEXT BoatNumber
PRINT "Number of boats available ", BoatsAvailable
display number of boats
© UCLES 2017
Marks
Page 4 of 8
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
465
Question
2
Answer
1 mark for each, there may be other solutions, award full marks for any working solution
any six from:
initialise total (outside loop)
Input number of numbers (outside loop with validation)
Loop using input value
Input number (inside loop)
Update Total (inside loop)
Calculate average
Print average and total (outside loop)
Sample algorithm:
INPUT NumberCount
Total Å 0
FOR Count Å 1 TO NumberCount
INPUT Number
Total Å Total + Number
NEXT
Average Å Total/NumberCount
PRINT Total, Average
© UCLES 2017
Page 5 of 8
October/November
2017
Marks
6
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
466
Question
3
Answer
4
Marks
1 mark for each correct line, max 3 marks.
3
Data Structure
Description
Constant
A collection of related data.
Array
A value that can change whilst
a program is running.
Table
A value that never changes
whilst a program is running.
Variable
A series of elements of the
same data type.
Question
Answer
2 marks for identification, 1 mark for description, 1 mark for reason.
Identification:
CASE …
… OF … OTHERWISE … (ENDCASE)or
… OF … (OTHERWISE) … ENDCASE
Description:
– a statement that allows for multiple selections // not any of the above
Reason:
– to simplify pseudocode/ make pseudocode more understandable etc.
© UCLES 2017
October/November
2017
Page 6 of 8
Marks
4
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
467
Question
Answer
5(a)
Accept
Reject
Count
0
0
0
1
50.4
2
2
50.3
3
49.1
3
4
50.3
4
5
50.0
5
6
49.5
6
7
50.2
7
8
50.3
8
9
50.5
10
50.6
2
© UCLES 2017
Å
(1 mark)
ÆÅ
–
–
change to Is Count = 50?
remove IS Sack > 50.5?
(1 mark)
ÆÅ
(1 mark)
Marks
Sack
1
1
5(b)
October/November
2017
ÆÅ
(1 mark)
5
OUTPUT
82
ÆÅ
(1 mark)
Æ
2
Page 7 of 8
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2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
468
Question
6(a)
October/November
2017
Answer
–
Marks
1 mark for each field suitable name, 1 mark for appropriate data type and appropriate data sample
6
The following are examples there are many different correct answers.
–
–
–
6(b)
6(c)
–
Engine Number, text, 21012
Class, text, P6
Service Date, date, 4/3/2017
Engine Number // Correct field number
Field: Engine Number
Table: TRAIN
1
Class
Service Date
TRAIN
TRAIN
3
Sort:
Show:
;
Criteria:
†
Like ‘P*’ // Like ‘P?’
†
<10/11/2016
or:
(1 mark)
© UCLES 2017
(1 mark)
(1 mark)
Page 8 of 8
†
.
469
Iteach Cambridge International Examinations
Cambridge Ordinary Level
* 6 5 9 3 9 4 9 7 3 1 *
2210/12
COMPUTER SCIENCE
Paper 1 Theory
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
Any businesses described in this paper are entirely fictitious.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 11 printed pages and 1 blank page.
DC (JM) 162278
© UCLES
[Turn over
.
2
470
1
Different units of data can be used to represent the size of a file, as it changes in size.
Fill in the missing units of data, using the list given:
•
byte
•
gigabyte (GB)
•
megabyte (MB)
•
nibble
The units of data increase in size from smallest to largest.
Smallest
bit
………………………………………………..
………………………………………………..
kilobyte (kB)
………………………………………………..
………………………………………………..
Largest
terabyte (TB)
[4]
2
(a) Nancy has captured images of her holiday with her camera. The captured images are stored
as digital photo files on her camera.
Explain how the captured images are converted to digital photo files.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [4]
© UCLES 2018
2210/12/M/J/18
.
3
471
(b) Nancy wants to email the photos to Nadia.
Many of the photos are very large files, so Nancy needs to reduce their file size as much as
possible.
Identify which type of compression would be most suitable for Nancy to use. Explain your
choice.
Compression type .....................................................................................................................
Explanation ...............................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[4]
3
A stopwatch uses six digits to display hours, minutes and seconds.
The stopwatch is stopped at:
0 2
3 1
5 8
Hours
Minutes
Seconds
An 8-bit register is used to store each pair of digits.
(a) Write the 8-bit binary numbers that are currently stored for the Hours, Minutes and Seconds.
Hours
Minutes
Seconds
[3]
© UCLES 2018
2210/12/M/J/18
[Turn over
.
4
472
(b) The stopwatch is started again and then stopped.
When the watch is stopped, the 8-bit binary registers show:
Hours
0
0
0
0
0
1
0
1
Minutes
0
0
0
1
1
0
1
0
Seconds
0
0
1
1
0
1
1
1
Write the denary values that will now be shown on the stopwatch.
Hours
Minutes
Seconds
[3]
4
Jafar is using the Internet when he gets the message:
“D03, page is not available”
Jafar remembers that hexadecimal is often used to represent binary values in error codes.
Convert the hexadecimal number in the error message into 12-bit binary.
[3]
© UCLES 2018
2210/12/M/J/18
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5
473
5
The three binary numbers in the registers X, Y and Z have been transmitted from one computer to
another.
Parity bit
Register X
1
0
0
1
0
0
1
0
Register Y
1
1
1
0
0
1
1
1
Register Z
1
1
1
0
1
0
0
1
Only one binary number has been transmitted correctly. This is identified through the use of a
parity bit.
Identify which register contains the binary number that has been transmitted correctly. Explain
the reason for your choice.
The binary number that has been transmitted correctly is in Register ............................................
Explanation ......................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[4]
© UCLES 2018
2210/12/M/J/18
[Turn over
.
6
474
6
Kelvin correctly answers an examination question about the Von Neumann model.
Eight different terms have been removed from his answer.
Complete the sentences in Kelvin’s answer, using the list given.
Not all items in the list need to be used.
•
accumulator (ACC)
•
address bus
•
arithmetic logic unit (ALU)
•
control unit (CU)
•
data bus
•
executed
•
fetches
•
immediate access store (IAS)
•
memory address register (MAR)
•
memory data register (MDR)
•
program counter (PC)
•
saved
•
transmits
The central processing unit (CPU) ....................................................................................
the data and instructions needed and stores them in the
.................................................................................... to wait to be processed.
The .................................................................................... holds the address of the next
instruction. This address is sent to the .................................................................................... .
The data from this address is sent to the .................................................................................... .
The instruction can then be decoded and .................................................................................... .
Any calculations that are carried out on the data are done by the
.................................................................................... . During calculations, the data is temporarily
held in a register called the .................................................................................... .
[8]
© UCLES 2018
2210/12/M/J/18
.
7
475
7
Consider the logic statement:
X = 1 if ((A is 1 AND B is NOT 1) NAND C is 1) XOR ((A is 1 AND C is 1) OR B is 1)
(a) Draw a logic circuit to represent the given logic statement.
A
B
X
C
[6]
(b) Complete the truth table for the given logic statement.
A
B
C
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
Working space
X
[4]
© UCLES 2018
2210/12/M/J/18
[Turn over
.
8
476
8
Dimitri is writing a computer program in a high-level language.
He needs to send just the machine code for the program to his friend, electronically.
It is important that the program is executed as quickly as possible.
Identify which translator will be most suitable for Dimitri to use. Explain your choice.
Type of translator .............................................................................................................................
Explanation ......................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
[4]
9
An advertisement in a magazine displays this barcode:
(a) Identify this type of barcode.
.............................................................................................................................................. [1]
(b) Explain how the data stored in this barcode is read.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [4]
© UCLES 2018
2210/12/M/J/18
.
9
477
10 Alexandra has a new mobile device.
It has a touch screen that uses capacitive technology.
(a) Describe how a capacitive touch screen registers Alexandra’s touch.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
.............................................................................................................................................. [4]
(b) Alexandra is wearing gloves because it is cold.
She presses an icon on her touch screen but her action is not registered.
(i)
Explain why the touch screen will not register her touch.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
(ii)
Alexandra does not want to remove her gloves.
Explain how Alexandra could use her mobile device whilst still wearing gloves.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [2]
© UCLES 2018
2210/12/M/J/18
[Turn over
.
410
78
11
A factory uses a security system to control a security light. The system uses a sensor and a
microprocessor.
Explain how the security system makes use of the sensor and the microprocessor to control the
security light.
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..........................................................................................................................................................
..................................................................................................................................................... [6]
© UCLES 2018
2210/12/M/J/18
.
411
79
12 (a) Selma has some important personal information that she needs to email to her employer.
She wants to make sure that if the personal information is intercepted, it cannot be understood.
(i)
State how Selma could email her personal data more securely.
...................................................................................................................................... [1]
(ii)
Describe how your chosen solution works.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...................................................................................................................................... [5]
(b) Selma wants to make sure that the information received is correct.
A parity check can be used to detect errors.
Describe another error detection method that can be used to check the information received
is correct.
Error detection method .............................................................................................................
Description ................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[3]
© UCLES 2018
2210/12/M/J/18
.
480
Cambridge Assessment International Education
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/12
Paper 1
May/June 2018
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the May/June 2018 series for most
Cambridge IGCSE™, Cambridge International A and AS Level and Cambridge Pre-U components, and
some Cambridge O Level components.
IGCSE™ is a registered trademark.
This document consists of 10 printed pages.
© UCLES 2018
[Turn over
2210/12
.
Cambridge O Level – Mark Scheme
PUBLISHED
481
Generic Marking Principles
May/June 2018
These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the
specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these
marking principles.
GENERIC MARKING PRINCIPLE 1:
Marks must be awarded in line with:
•
•
•
the specific content of the mark scheme or the generic level descriptors for the question
the specific skills defined in the mark scheme or in the generic level descriptors for the question
the standard of response required by a candidate as exemplified by the standardisation scripts.
GENERIC MARKING PRINCIPLE 2:
Marks awarded are always whole marks (not half marks, or other fractions).
GENERIC MARKING PRINCIPLE 3:
Marks must be awarded positively:
•
•
•
•
•
marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the
scope of the syllabus and mark scheme, referring to your Team Leader as appropriate
marks are awarded when candidates clearly demonstrate what they know and can do
marks are not deducted for errors
marks are not deducted for omissions
answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the
question as indicated by the mark scheme. The meaning, however, should be unambiguous.
GENERIC MARKING PRINCIPLE 4:
Rules must be applied consistently e.g. in situations where candidates have not followed instructions or in the application of generic level
descriptors.
© UCLES 2018
Page 2 of 10
2210/12
GENERIC MARKING PRINCIPLE 5:
.
Cambridge O Level – Mark Scheme
PUBLISHED
482
May/June 2018
Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may
be limited according to the quality of the candidate responses seen).
GENERIC MARKING PRINCIPLE 6:
Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or
grade descriptors in mind.
© UCLES 2018
Page 3 of 10
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
483
Question
1
Answer
1 mark for each unit, in the given order:
–
–
nibble
byte
–
–
megabyte (MB)
gigabyte (GB)
May/June 2018
Marks
4
Question
Answer
Marks
2(a)
Any four from:
– Image is converted from analogue to digital (using ADC)
– Image is turned into pixels
– Each pixel is given a binary value
– Pixels form a grid (to create the image)
– Each pixel has a colour
– Pixels are stored in sequence (in a file)
– Meta data is stored (to describe the dimensions/resolution of the image) // It stores the dimensions/colour
depth .etc.
– An example of a suitable photo file format e.g. JPEG
4
2(b)
1 mark for correct compression, 3 marks for explanation:
4
–
Lossy
Any three from:
– Lossy would reduce the file size more (than lossless)
– The redundant data can be removed from the files // by example (must be about redundant data)
– Images can still be a similar quality
– There is no requirement for the files to be exactly the same as original file
– Photos can be sent quicker // faster to upload // faster to download
© UCLES 2018
Page 4 of 10
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
484
Question
3(a)
3(b)
Answer
3
Hours
0
0
0
0
0
0
1
0
Minutes
0
0
0
1
1
1
1
1
Seconds
0
0
1
1
1
0
1
0
1 mark for each correct section:
3
5
2
Hours
6
5
Minutes
Question
5
Seconds
Answer
Marks
1 mark for each correct section:
1
1
0
1 mark
© UCLES 2018
Marks
1 mark for each correct register
0
4
May/June 2018
1
3
0
0
0
0
1 mark
0
0
1
1 mark
Page 5 of 10
1
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2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
485
Question
5
Answer
1 mark for correct register, 3 marks for reason:
–
May/June 2018
Marks
4
Register Y
Any three from:
– Count the number of 1/0 bits (in each byte/register)
– Two bytes/registers have an odd number of 1/0 bits // Two have odd parity
– Even parity must be the parity used
– One byte/register has an even number of 1/0 bits // One uses even parity
– The two with an odd number of one bits/odd parity are incorrect // Register X and Z should have even parity
Question
6
Answer
1 mark for each correct missing word, in the given order:
–
–
–
–
–
–
–
–
© UCLES 2018
fetches
immediate access store // IAS
program counter // PC
memory address register // MAR
memory data register // MDR
executed
arithmetic logic unit // ALU
accumulator // ACC
Page 6 of 10
Marks
8
.
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Cambridge O Level – Mark Scheme
PUBLISHED
486
Question
Answer
May/June 2018
Marks
7(a)
1 mark for each correct logic gate with correct direct of input(s):
6
7(b)
4 marks for 8 correct outputs
3 marks for 6 or 7 correct outputs
2 marks for 4 or 5 correct outputs
1 mark for 2 or 3 correct outputs
4
© UCLES 2018
A
B
C
Working space
X
0
0
0
1
0
0
1
1
0
1
0
0
0
1
1
0
1
0
0
1
1
0
1
1
1
1
0
0
1
1
1
0
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2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
487
Question
8
Answer
1 mark for correct translator, 3 marks for explanation:
–
May/June 2018
Marks
4
Compiler
Any three from:
– Does not require recompilation // compiled program can be executed without a compiler «
– ... therefore, allows faster execution
– Provides an executable file «
– « therefore, allows him to just send machine code
– Dimitri’s friend does not need translation/compilation software to execute the program
Question
Answer
Marks
9(a)
QR/Quick response
1
9(b)
Any four from:
– Read/scanned using app (on mobile device)
– It is the camera that is used to scan/capture the image
– The three large squares are used to define the alignment // uses alignment targets/modules
– Black squares reflect less light // white squares reflect more light
– The app/device processes the image
– Each small square/pixel is converted to a binary value
4
Question
10(a)
© UCLES 2018
Answer
Any four from:
– Conductive layer
– An electrostatic/electric field is created
– Sensor(s) (around the screen) monitor the electrostatic field
– When touched (electrostatic) charge is transferred to finger
– Location of touch is calculated // Co-ordinates used to calculate touch
Page 8 of 10
Marks
4
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
488
Question
Answer
May/June 2018
Marks
10(b)(i)
Any two from:
– Gloves are not conductive // Gloves are an insulator
– Block current/charge from finger / body / person
– Stop the electrostatic field being disturbed/changed
2
10(b)(ii)
Any two from e.g. (1 mark for method, 1 for expansion):
– She could use a (conductive) stylus«
– « this will allow the charge to be charged/disturbed
2
–
–
She could use capacitive gloves«
« this will allow the charge to be charged/disturbed
–
–
She could use a natural language interface/voice operated interface «
« she could give vocal commands to the device
Question
11
Answer
Any six from:
– Suitable sensor (motion/infra-red)
– Data converted (from analogue) to digital (using ADC)
– Data sent to microprocessor
– Data is compared to stored value/range «
– « if data matches/out of range data security light turned on «
– « waits for suitable period/until no motion detected «
– « light turned off
– Continuous loop/process
Question
12(a)(i)
© UCLES 2018
Answer
Encryption
Marks
6
Marks
1
Page 9 of 10
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2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
489
Question
12(a)(ii)
12(b)
Answer
Marks
Any five from:
– Her personal details before encryption is the plain text
– The plain text/her personal details is encrypted using an encryption algorithm
– The plain text/her personal details is encrypted using a key
– The encrypted text is cypher/cipher text
– The key is transmitted separately (from the text)
– The key is used to decrypt the cypher text (after transmission)
5
Any three from a single error method:
– Checksum
– Calculation carried out on data
– (checksum/calculated) value sent with data
– recalculated after transmission and compared to original
– If they do not match an error is present
3
–
–
–
–
–
© UCLES 2018
May/June 2018
ARQ
uses acknowledgment and timeout
A request is sent with data to acknowledge all data is received
Acknowledgement sent back to say all data is received
If no acknowledgement is received in a time frame an error in transmission detected / data automatically resent.
Page 10 of 10
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490
Cambridge International Examinations
Cambridge Ordinary Level
* 6 4 3 3 3 4 7 1 7 2 *
2210/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
May/June 2018
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 11 printed pages and 1 blank page.
DC (KS) 160594
© UCLES 2018
[Turn over
.
2
491
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release material
A farmer records the milk production of a herd of cows. Every cow has a unique 3-digit identity
code. Each cow can be milked twice a day, seven days a week. The volume of milk from each cow
is recorded in litres correct to one decimal place (yield) every time the cow is milked. The size of the
herd is fixed. At the end of the week the total and the average yield for each cow for that week is
calculated.
The farmer identifies the cow that has produced the most milk that week. The farmer also identifies
any cows that have produced less than 12 litres of milk on four or more days that week.
A program is required to record the yield for each cow every time it is milked, calculate the total
weekly volume of milk for the herd and the average yield per cow in a week. The program must also
identify the cow with the best yield that week and identify any cows with a yield of less than 12 litres
of milk for four or more days that week.
Write and test a program or programs for the farmer.
•
•
•
Your program or programs must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly and understandably.
All variables, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Record the yield.
Write a program for TASK 1 to record the milk yields for a week. The program records and stores the
identity code number and the yield every time a cow is milked.
TASK 2 – Calculate the statistics.
Using your recorded data from TASK 1, calculate and display the total weekly volume of milk for
the herd to the nearest whole litre. Calculate and display the average yield per cow in a week to the
nearest whole litre.
TASK 3 – Identify the most productive cow and cows that are producing a low volume of milk.
Extend TASK 2 to identify and display the identity code number and weekly yield of the cow that has
produced the most milk. Also identify and display the identity code numbers of any cows with a yield
of less than 12 litres of milk for four days or more in the week.
© UCLES 2018
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492
1
(a) All variables, constants and other identifiers should have meaningful names.
(i)
State the name, the data type and the use of two variables that you have used in Task 2.
Variable 1 name ................................................................................................................
Data type ...........................................................................................................................
Use ....................................................................................................................................
Variable 2 name ................................................................................................................
Data type ...........................................................................................................................
Use ....................................................................................................................................
[2]
(ii)
Describe, with the aid of some sample data, the data structures that you have used to
record the data for the cows in Task 1.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[4]
(b) Explain how your program for Task 1 ensures that each 3-digit identity code is unique.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
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493
(c) Write an algorithm for Task 2, using either pseudocode, programming statements or a
flowchart. Assume that Task 1 has been completed.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[5]
© UCLES 2018
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5
494
(d) (i)
Explain how your program for Task 3 finds the cows with a daily yield of less than
12 litres of milk for four days or more in the week. Any programming statements used in
your answer must be fully explained.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[5]
(ii)
Explain how you would extend your program for Task 3 to store the identity code
number(s) of those cows with a yield of less than 12 litres of milk for four days or more in
the week.
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
...........................................................................................................................................
.......................................................................................................................................[2]
© UCLES 2018
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495
Section B
2
(a) Draw a flowchart for an algorithm to input numbers. Reject any numbers that are negative
and count how many numbers are positive. When the number zero is input, the process ends
and the count of positive numbers is output.
[6]
© UCLES 2018
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496
(b) Explain the changes you will make to your algorithm to also count the negative numbers.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
Question 3 starts on Page 8.
© UCLES 2018
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497
3
This pseudocode algorithm inputs two non-zero numbers and a sign, and then performs the
calculation shown by the sign. An input of zero for the first number terminates the process.
INPUT
WHILE
IF
IF
IF
IF
IF
Number1, Number2, Sign
Number1 <> 0
Number1 + Number2
Sign = '+' THEN Answer
Number1 - Number2
Sign = '-' THEN Answer
Number1 * Number2
Sign = '*' THEN Answer
Number1 / Number2
Sign = '/' THEN Answer
Sign <> '/' AND Sign <> '*' AND Sign <> '-'
0
THEN Answer
ENDIF
IF Answer <> 0 THEN OUTPUT Answer ENDIF
INPUT Number1, Number2, Sign
ENDWHILE
ENDIF
ENDIF
ENDIF
ENDIF
AND Sign <> '+'
(a) Complete the trace table for the input data:
5, 7, +, 6, 2, –, 4, 3, , 7, 8, ?, 0, 0, /
*
Number1
Number2
Sign
Answer
OUTPUT
[3]
(b) Show how you could improve the algorithm written in pseudocode by writing an alternative
type of conditional statement in pseudocode.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[3]
© UCLES 2018
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9
498
4
A programmer has written a routine to store the name, email address and password of a contributor
to a website’s discussion group.
(a) The programmer has chosen to verify the name, email address and password.
Explain why verification was chosen and describe how the programmer would verify this data.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[4]
(b) The programmer has also decided to validate the email address and the password.
Describe validation checks that could be used.
Email address ............................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
Password ..................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
[2]
© UCLES 2018
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99
5
A program checks that the weight of a basket of fruit is over 1.00 kilograms and under
1.10 kilograms. Weights are recorded to an accuracy of two decimal places and any weight not in
this form has already been rejected.
Give three weights as test data and for each weight state a reason for choosing it. All your reasons
must be different.
Weight 1 ............................................................................................................................................
Reason ..............................................................................................................................................
..........................................................................................................................................................
Weight 2 ............................................................................................................................................
Reason ..............................................................................................................................................
..........................................................................................................................................................
Weight 3 ............................................................................................................................................
Reason ..............................................................................................................................................
..........................................................................................................................................................
[3]
© UCLES 2018
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511
00
6
A database table, TREES, is used to keep a record of the trees in a park. Each tree is given a
unique number and is examined to see if it is at risk of dying. There are over 900 trees; part of the
database table is shown.
Tree Number
Type
Map Position
Age in Years
At Risk
TN091
Acacia
A7
250
Y
TN172
Olive
C5
110
N
TN913
Cedar
B9
8
N
TN824
Banyan
A3
50
Y
TN021
Pine
D5
560
Y
TN532
Teak
C8
76
Y
TN043
Yew
B1
340
N
TN354
Spruce
D4
65
N
TN731
Elm
B10
22
Y
TN869
Oak
C9
13
N
TN954
Pine
E11
3
N
(a) State the number of fields in the table.
...............................................................................................................................................[1]
(b) The tree numbering system uses TN followed by three digits. The numbering system will not
work if there are over 1000 trees.
Describe, with the aid of an example, how you could change the tree numbering system to
allow for over 1000 trees. Existing tree numbers must not be changed.
...................................................................................................................................................
...................................................................................................................................................
...................................................................................................................................................
...............................................................................................................................................[2]
(c) Using the query-by-example grid, write a query to identify at risk trees over 100 years old.
Display only the type and the position on the map.
Field:
Table:
Sort:
Show:
Criteria:
or:
[4]
© UCLES 2018
2210/22/M/J/18
.
501
Cambridge Assessment International Education
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/22
Paper 2
May/June 2018
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the May/June 2018 series for most
Cambridge IGCSE™, Cambridge International A and AS Level and Cambridge Pre-U components, and
some Cambridge O Level components.
IGCSE™ is a registered trademark.
This document consists of 7 printed pages.
© UCLES 2018
[Turn over
2210/22
.
Cambridge O Level – Mark Scheme
PUBLISHED
502
May/June 2018
Generic Marking Principles
These general marking principles must be applied by all examiners when marking candidate answers.
They should be applied alongside the specific content of the mark scheme or generic level descriptors
for a question. Each question paper and mark scheme will also comply with these marking principles.
GENERIC MARKING PRINCIPLE 1:
Marks must be awarded in line with:
•
•
•
the specific content of the mark scheme or the generic level descriptors for the question
the specific skills defined in the mark scheme or in the generic level descriptors for the question
the standard of response required by a candidate as exemplified by the standardisation scripts.
GENERIC MARKING PRINCIPLE 2:
Marks awarded are always whole marks (not half marks, or other fractions).
GENERIC MARKING PRINCIPLE 3:
Marks must be awarded positively:
•
•
•
•
•
marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit
is given for valid answers which go beyond the scope of the syllabus and mark scheme,
referring to your Team Leader as appropriate
marks are awarded when candidates clearly demonstrate what they know and can do
marks are not deducted for errors
marks are not deducted for omissions
answers should only be judged on the quality of spelling, punctuation and grammar when these
features are specifically assessed by the question as indicated by the mark scheme. The
meaning, however, should be unambiguous.
GENERIC MARKING PRINCIPLE 4:
Rules must be applied consistently e.g. in situations where candidates have not followed
instructions or in the application of generic level descriptors.
GENERIC MARKING PRINCIPLE 5:
Marks should be awarded using the full range of marks defined in the mark scheme for the question
(however; the use of the full mark range may be limited according to the quality of the candidate
responses seen).
GENERIC MARKING PRINCIPLE 6:
Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should
not be awarded with grade thresholds or grade descriptors in mind.
© UCLES 2018
Page 2 of 7
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2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
503
Question
May/June 2018
Answer
Marks
Section A
1(a)(i)
Variable name, data type and use one mark, max two
Several correct answers, the names chosen must be meaningful. Variables must
relate to task 2
Example
Name
Data type
Use
Name
Data type
Use
1(a)(ii)
2
totalMilk
integer/real
to store the total volume of the milk for the week (to the nearest
whole litre) (1)
weeklyAverage
integer/real
to store the average yield per week (1)
One mark per bullet point.
• Data structure(s) given (1)
• Data type (1)
• Sample data (1)
• More than one data structure described (1)
4
Example
A real array for each milking and an array of strings for the identity codes. There
would be 14 arrays for the milking e.g. mondayMorning, mondayEvening
Sample data for a cow could be 123, 23.5, 22.7
1(b)
Entering/selecting the identity code (1) method to ensure it is not a duplicate (1)
Example
Enter new identity code number
Check if already in the list of code numbers
© UCLES 2018
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2
2210/22
Question
1(c)
.
Cambridge O Level – Mark Scheme
PUBLISHED
504
May/June 2018
Answer
Any five from:
1 Initialisation for total weekly volume
2 loop control
3 calculation of running total for yield
4 calculation of average yield
5 output total and average yield per week with message outside loop
6 value(s) rounded
Marks
5
Sample answer
total ← 0
FOR counter ← 1 TO numCows
total ← total + mondayMorning(counter)
total ← total + mondayEvening(counter)
total ← total + tuesdayMorning(counter)
total ← total + tuesdayEvening (counter)
total ← total + wednesdayMorning(counter)
total ← total + wednesdayEvening (counter)
total ← total + thursdayMorning(counter)
total ← total + thursdayEvening (counter)
total ← total + fridayMorning(counter)
total ← total + fridayEvening (counter)
total ← total + saturdayMorning(counter)
total ← total + saturdayEvening (counter)
total ← total + sundayMorning(counter)
total ← total + sundayEvening(counter)
NEXT counter
Average ← ROUND(total/numCows)
OUTPUT "Total volume of milk for week ", ROUND(total)
OUTPUT "Average weekly yield ", average
1(d)(i)
Explanation
Any five from:
1 Check each cow
2 Initialise day counter to zero
3 Check every day of the week
4 If daily yield is less than 12
5
add one to day counter
6 If day counter >= 4
7
identify/output identity code number(s)
5
1(d)(ii)
Explanation
• Add new storage space to store code numbers for example new
array/table/list
• Add extra code to store these values if the condition was met
2
© UCLES 2018
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2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
505
Question
May/June 2018
Answer
Marks
Section B
2(a)
One mark per correct pair of actions, process, Input/Output, Tests (apart from
START and END) max 3
One mark complete Flowlines, one mark working flowlines, one mark correct use
flowchart symbols
6
START
Count
←
0
INPUT
Number
Is
Number
= 0?
Yes
No
Yes
Is
Number
< 0?
No
Count
2(b)
© UCLES 2018
OUTPUT Count, "
positive
numbers"
← Count + 1
END
Any two from:
• Use another counter/variable
• Update this counter/variable when the number is less than zero/count all
numbers and subtract the positive numbers
• Output this counter/variable at the end // Output both counters at the end
Page 5 of 7
2
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
506
Question
3(a)
Answer
Number1 Number2 Sign
Å
3(b)
Question
4(a)
May/June 2018
Marks
Answer
OUTPUT
5
7
+
12
12
6
2
-
4
4
4
3
*
12
12
7
8
?
0
0
0
/
(0)
1 mark
Æ Å 1 mark
Æ Å 1 mark
3
Æ
CASE Sign OF
ENDCASE (1)
List +, -, *, / with correct assignments (1)
OTHERWISE Answer ← 0 (1)
Example
CASE Sign OF
ꞌ+ꞌ : Answer ← Number1 + Number2
ꞌ-ꞌ : Answer ← Number1 - Number2
ꞌ*ꞌ : Answer ← Number1 * Number2
ꞌ/ꞌ : Answer ← Number1 / Number2
OTHERWISE Answer ← 0
ENDCASE
Answer
Max 4 in total
Any 3 from:
• To ensure no changes are made on input / accuracy of transcription
• Because the details do not have fixed, values or lengths to validate
• Because there is no clear set of rules that can be used for validation
3
Marks
4
Any 3 from:
• The programmer could ask the contributor to type in each detail twice
•
and then check that both values are equal
•
If they are not equal then the input should be rejected
• The programmer could ask the contributor to check the details on the
screen
•
and confirm that they are correct / same as the original
•
or change them
4(b)
One mark for email and one mark for password
Email – check for @ / format check / no spaces /valid characters // presence
check // length check (not more than 254 characters) // uniqueness check
Password – length check / numbers and letters etc. // uniqueness check not been
used before // presence check
© UCLES 2018
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2
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
507
Question
5
May/June 2018
Answer
Marks
One mark per value and reason, max 3
Example
1.00 – boundary rejected//rejected (underweight) // out of range(1)
1.02 – normal // valid // accepted weight in range (1)
1.10 – abnormal // erroneous // invalid // rejected (overweight) (1)
Question
3
Answer
Marks
6(a)
Fields
5
6(b)
One mark description of new code that will allow more than 1000 values
One mark for example matching candidate’s description
1
2
Example
Use a new character instead of N
TT345
6(c)
Field: At Risk
Table: TREES
Age in Years
Type
Map Position
TREES
TREES
TREES
Sort:
Show:
†
Criteria: True
†
>100
or:
One mark per correct column
© UCLES 2018
Page 7 of 7
;
;
4
.
508
Cambridge International Examinations
Cambridge Ordinary Level
* 1 6 9 9 0 2 9 4 0 9 *
2210/22
COMPUTER SCIENCE
Paper 2 Problem-solving and Programming
October/November 2018
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
DO NOT ATTEMPT TASKS 1, 2 AND 3 in the pre-release material; these are for information only.
You are advised to spend no more than 40 minutes on Section A (Question 1).
No marks will be awarded for using brand names of software packages or hardware.
Any businesses described in this paper are entirely fictitious.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 50.
This document consists of 11 printed pages and 1 blank page.
DC (SC) 173734
© UCLES 2018
[Turn over
.
2
509
Section A
You are advised to spend no longer than 40 minutes answering this section.
Here is a copy of the pre-release material.
DO NOT attempt Tasks 1, 2 and 3 now.
Use the pre-release material and your experience from attempting the tasks before the examination to
answer Question 1.
Pre-release material
A junior park run event is held every week on a Saturday morning in a local park over a distance of
two kilometres. Children between the ages of 4 and 14 inclusive can register to take part. Children
register with their name and age. When they register, they are allocated a unique identification
number of four digits; the last digit is a check digit. Once registered a child can take part in junior
park run events for a year.
For each event, the organisers record the time each child takes to run two kilometres. Their time is
stored for every event they complete and the number of runs they have completed is updated by
one. If their time is faster than their personal best (PB) time, their PB time is updated. When a child
has completed 11 runs, they are awarded a half-marathon wristband. When a child has completed
22 runs, they are awarded a full-marathon wristband.
A program is required to update the children’s data, update PB times if necessary, and decide if a
wristband is to be awarded. The program also needs to identify the fastest child at this event for
each of the age ranges: 4 to 6, 7 to 10 and 11 to 14.
Write and test a program or programs for the park run organiser.
•
•
•
Your program or programs must include appropriate prompts for the entry of data.
Error messages and other output need to be set out clearly and be understandable.
All variables, arrays, constants and other identifiers must have meaningful names.
You will need to complete these three tasks. Each task must be fully tested.
TASK 1 – Registering to take part.
Write a program to set up arrays to store the data for 20 children. On registration, each child must
be allocated a unique identification number of four digits; the last digit is a check digit. The unique
identification number, age in years and name for each child is recorded and stored on registration.
The PB time and the number of runs are initialised to zero and these values stored on registration.
Their PB time is stored as minutes correct to two decimal places.
TASK 2 – Recording the times.
Extend your program to record the unique identification number and to input the start time and finish
time for every child completing the junior park run event. Calculate and store the time each child
took to complete the run. A registered child does not have to compete in each event. Only one time
per child is recorded during an event.
TASK 3 – Updating the children’s data and identifying the fastest child for each age range.
Extend your program to update the number of runs and the PB time if necessary for every child
completing the junior park run event. Check if any half- or full-marathon wristbands need to be
awarded. Output the names and the type of wristbands. Output the names and the times of the
fastest child at this event for each of the age ranges 4 to 6, 7 to 10 and 11 to 14.
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(a) All variables, arrays, constants and other identifiers should have meaningful names.
(i)
State the name of one variable you have used for Task 3.
Give the data type for the variable. State what it is used for.
Variable name ...................................................................................................................
Data type ...........................................................................................................................
Use ....................................................................................................................................
[3]
(ii)
Describe the arrays that you have used to store the data for the children in Task 1.
Include the name, data type and its use for each array.
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(b) Explain how you ensured that each identification number entered in Task 1 was unique and
included a correct check digit.
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(c) Write an algorithm for Task 2, using either pseudocode, programming statements or a
flowchart. You should assume that Task 1 has already been completed.
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(d) Explain how your program identifies and outputs the names and times of the fastest runner
for each age range in Task 3. Any programming statements used in your answer must be
fully explained. Do not include the wristband check or PB time update.
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Section B
2
(a) Write an algorithm, using pseudocode, to input three different numbers, multiply the two
larger numbers together and output the result. Use the variables: Number1, Number2 and
Number3 for your numbers and Answer for your result.
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(b) Give two sets of test data to use with your algorithm in part (a) and explain why you chose
each set.
Test data set 1 ..........................................................................................................................
Reason .....................................................................................................................................
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Test data set 2 ..........................................................................................................................
Reason .....................................................................................................................................
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[4]
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3
Four programming concepts and four descriptions are shown.
Draw a line to connect each programming concept to the most appropriate description.
Programming concept
Description
Library routine
A subroutine that does not
have to return a value.
Structure
diagram
A standard subroutine that is
available for immediate use.
Procedure
A subroutine that always
returns a value.
Function
An overview of a program or
subroutine.
[3]
4
A programmer wants to test that the readings from 2000 electricity meters are greater than 400
units and less than 900 units. The programmer uses selection and repetition statements as part of
the program.
Explain, using programming statements, how selection and repetition could be used in this
program.
Selection ..........................................................................................................................................
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Repetition .........................................................................................................................................
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[4]
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BLANK PAGE
Question 5 starts on page 10.
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5
The flowchart checks the level of chlorine and the depth of water compared to the height of the
swimming pool. Error messages are output if a problem is found.
START
INPUT Height,
Depth, Chlorine
OK
True
Is Depth >
Height/2 ?
OUTPUT
"Water too
deep"
Yes
No
Is Depth <
Height/3 ?
OUTPUT
"Water too
shallow"
Yes
No
Is Chlorine
>3 ?
OK
Yes
False
OUTPUT "Too
much chlorine
add more water"
No
Is Chlorine
<1 ?
Yes
OUTPUT "Too
little chlorine
add more chlorine"
No
No
Is OK = True ?
Yes
OUTPUT "Pool OK
to use"
END
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(a) Complete the trace tables for each set of input data.
Input data: 6, 2.5, 2
Height
Depth
Chlorine
OK
OUTPUT
Chlorine
OK
OUTPUT
Chlorine
OK
OUTPUT
Input data: 4, 3, 1.5
Height
Depth
Input data: 6, 3.5, 4
Height
Depth
[6]
(b) Identify a problem with the algorithm that the flowchart represents.
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6
A database table, PORTRAIT, is used to keep a record of the portraits available from a photographic
studio. Each portrait has a unique reference number PICnnn, where n is a single digit, for example
PIC123. The studio keeps a record of the size (for example 20 × 15), the type (black and white or
colour), and the price in dollars.
(a) Complete the table to show the most appropriate data type for each of the fields.
Field
Data type
Reference Number
Size
Type
Price in $
[4]
(b) The results from the query-by-example grid should show the reference number, price, type
and size of all portraits under $50. Identify the three errors in the query-by-example grid.
Field:
Reference No
Price in $
Type
Size
Table:
PORTRAIT
PORTRAIT
PORTRAIT
PORTRAIT
Sort:
Show:
Criteria:



>50.00
or:
Error 1 .......................................................................................................................................
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Error 2 .......................................................................................................................................
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Error 3 .......................................................................................................................................
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[3]
Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every
reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the
publisher will be pleased to make amends at the earliest possible opportunity.
To avoid the issue of disclosure of answer-related information to candidates, all copyright acknowledgements are reproduced online in the Cambridge International
Examinations Copyright Acknowledgements Booklet. This is produced for each series of examinations and is freely available to download at www.cie.org.uk after
the live examination series.
Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local
Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.
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520
Cambridge International Examinations
Cambridge Ordinary Level
* 7 2 5 2 4 7 4 5 5 8 *
2210/12
COMPUTER SCIENCE
Paper 1 Theory
October/November 2018
1 hour 45 minutes
Candidates answer on the Question Paper.
No Additional Materials are required.
No calculators allowed.
READ THESE INSTRUCTIONS FIRST
Write your Centre number, candidate number and name in the spaces at the top of this page.
Write in dark blue or black pen.
You may use an HB pencil for any diagrams, graphs or rough working.
Do not use staples, paper clips, glue or correction fluid.
DO NOT WRITE IN ANY BARCODES.
Answer all questions.
No marks will be awarded for using brand names of software packages or hardware.
Any businesses described in this paper are entirely fictitious.
At the end of the examination, fasten all your work securely together.
The number of marks is given in brackets [ ] at the end of each question or part question.
The maximum number of marks is 75.
This document consists of 11 printed pages and 1 blank page.
DC (KS) 171196
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1
Computers use a character set to convert text into binary.
One character set that can be used is ASCII.
Each letter in ASCII can also be represented as a denary value.
(a) The word BUS has the denary values:
B
U
S
66
85
83
Convert the denary values into 8-bit binary.
66
85
83
[3]
(b) Each letter in ASCII can also be represented as a hexadecimal value.
The word KEY has the 8-bit binary values:
(i)
K
E
Y
01001011
01000101
01011001
Convert the three 8-bit binary values into hexadecimal.
01001011
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01000101
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01011001
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[3]
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(ii)
Give three other uses of hexadecimal notation in computer science.
1 .........................................................................................................................................
2 .........................................................................................................................................
3 .........................................................................................................................................
[3]
(iii)
State two benefits of using hexadecimal notation to represent binary values.
Benefit 1 ............................................................................................................................
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Benefit 2 ............................................................................................................................
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[2]
2
A computer uses RAM and ROM to store data.
(a) The table contains three statements about RAM or ROM.
Tick (✓) to show whether each statement describes RAM or ROM.
Statement
RAM
(✓)
ROM
(✓)
Stores the programs and data that are currently in use
Used to boot up the computer when power is turned on
Contents are retained when power is turned off
[3]
(b) Circle the storage category that includes both RAM and ROM.
Primary
Secondary
Off-line
[1]
(c) Explain what is meant by off-line storage.
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3
A greenhouse uses a system to monitor the conditions that plants need to grow.
The inputs to the system are:
Binary
value
Input
W
T
H
Condition
1
Window is open
0
Window is closed
1
Temperature >=26 °C
0
Temperature <26 °C
1
Humidity >=50%
0
Humidity <50%
The system will sound an alarm when certain conditions are detected.
Alarm (X) will sound (=1) when:
window is closed and temperature >=26 °C
or
temperature <26 °C and humidity >=50%
Draw a logic circuit to represent the system.
W
T
X
H
[5]
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(a) Identify three security issues that can put a computer system at risk.
Security issue 1 ........................................................................................................................
Security issue 2 ........................................................................................................................
Security issue 3 ........................................................................................................................
[3]
(b) Explain how a firewall can help to protect a computer system from security issues.
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5
(a) Karina is taking her Computer Science examination. She has three questions to answer
about output devices.
(i)
For the first question she writes the answer:
“It is a high powered laser that cuts materials such as thin metals or wood.”
Identify the output device that Karina is describing.
.......................................................................................................................................[1]
(ii)
For the second question she writes the answer:
“The screen is made up of blocks of red, green and blue pixels. The screen uses layers
of different types of liquid.”
Identify the output device that Karina is describing.
.......................................................................................................................................[1]
(iii)
For the third question she writes the answer:
“It is responsible for powering and moving a motor in machinery, such as a robot arm in
a factory.”
Identify the output device that Karina is describing.
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(b) Karina correctly answers another examination question about some more output devices.
Five different terms have been removed from her answer.
Complete the sentences in Karina’s answer, using the list given. Not all terms in the list need
to be used.
•
•
•
•
•
•
•
•
•
•
3D
digital light projector
inkjet
interactive whiteboard
laser
rotating
scanning
sliding
speaker
thermal bubble
An ................................................................................................... allows a user to write on a
surface using a pen, the text and drawings can then be captured and stored for later use.
An ................................................................................................... printer produces a hard
copy of a document using ................................................................................................... and
piezoelectric technology. A ...................................................................................................
printer uses a .............................................................................................. drum, and positive
and negative charges, to produce a hard copy of a document.
[5]
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(a) Many programmers write computer programs in high-level languages. The programs need to
be translated into machine code to be read by the computer.
State two types of translator that can be used.
Translator 1 ...............................................................................................................................
Translator 2 ...............................................................................................................................
[2]
(b) Explain two reasons why a computer programmer may choose to write a program in a highlevel language, rather than a low-level language.
Reason 1 ..................................................................................................................................
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Reason 2 ..................................................................................................................................
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[4]
(c) Three examples of computer code are given in the table.
Tick (✓) to show whether each example of computer code is High-level language, Assembly
language or Machine code.
Computer code
High-level
language
(✓)
Assembly
language
(✓)
Machine
code
(✓)
10110111
11001100
01011100
FOR X = 1 TO 10
PRINT X
NEXT X
INP X
STA X
LDA Y
[3]
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7
Six internet terms and six definitions are listed.
Draw a line to connect each term to a correct definition.
Internet term
Definition
Browser
A program that allows a user to view
webpages
Internet Service Provider
(ISP)
The main protocol that governs the
transmission of data using the Internet
Hyper Text Transfer Protocol
(HTTP)
The website address that is typed into the
address bar
Uniform Resource Locator
(URL)
An address given to each device on a network.
It is provided by the network
MAC address
A unique address given to a device on a
network. It is provided by the manufacturer
IP address
A company that provides a connection to
access the Internet
[5]
8
Describe the purpose of an interrupt in a computer system.
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(a) Computers can transmit data using different methods.
Describe the three data transmission methods given.
(i)
Serial data transmission
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(ii)
Parallel data transmission
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(iii)
Duplex data transmission
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(b) Data can sometimes be corrupted when it is transmitted from one computer to another,
causing errors to be present in the data.
Identify and describe three methods of error detection that could be used to see if an error
has occurred.
Error detection method 1 ..........................................................................................................
Description ................................................................................................................................
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Error detection method 2 ..........................................................................................................
Description ................................................................................................................................
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Error detection method 3 ..........................................................................................................
Description .................................................................................................................................
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[9]
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10 A system uses pH sensors and a microprocessor to help monitor pollution in a river.
The pH of the water should be between 6 and 8. The system outputs an alert if the pH of the water
is not in this range.
Explain how the system uses the pH sensors and the microprocessor to help monitor the pollution.
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Cambridge Assessment International Education
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/22
Paper 2
October/November 2018
MARK SCHEME
Maximum Mark: 50
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the October/November 2018 series for most
Cambridge IGCSE™, Cambridge International A and AS Level components and some Cambridge O Level
components.
This document consists of 11 printed pages.
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Generic Marking Principles
October/November 2018
These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the
specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these
marking principles.
GENERIC MARKING PRINCIPLE 1:
Marks must be awarded in line with:
•
•
•
the specific content of the mark scheme or the generic level descriptors for the question
the specific skills defined in the mark scheme or in the generic level descriptors for the question
the standard of response required by a candidate as exemplified by the standardisation scripts.
GENERIC MARKING PRINCIPLE 2:
Marks awarded are always whole marks (not half marks, or other fractions).
GENERIC MARKING PRINCIPLE 3:
Marks must be awarded positively:
•
•
•
•
•
marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the
scope of the syllabus and mark scheme, referring to your Team Leader as appropriate
marks are awarded when candidates clearly demonstrate what they know and can do
marks are not deducted for errors
marks are not deducted for omissions
answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the
question as indicated by the mark scheme. The meaning, however, should be unambiguous.
GENERIC MARKING PRINCIPLE 4:
Rules must be applied consistently e.g. in situations where candidates have not followed instructions or in the application of generic level
descriptors.
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GENERIC MARKING PRINCIPLE 5:
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Cambridge O Level – Mark Scheme
PUBLISHED
533
October/November 2018
Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may
be limited according to the quality of the candidate responses seen).
GENERIC MARKING PRINCIPLE 6:
Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or
grade descriptors in mind.
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Question
Answer
October/November 2018
Marks
Section A
1(a)(i)
Many correct answers, they must be meaningful. The name is an example only.
3
1 mark per bullet point
•
•
•
1(a)(ii)
Variable name
Data type
Use
Winner4to6
string
storing the unique id of the runner age 4 to 6 with the fastest time
Many correct answers, they must be meaningful. The names are examples only.
1 mark per bullet point
•
•
•
•
•
5 arrays seen
At least one suitable name e.g. IdNumber
At least one suitable datatype e.g. string
At least one suitable use e.g. to store the unique identification number
All 5 names, datatypes and uses correct
Array examples
Array name
IdNumber
Name
Age
NumRuns
PB
© UCLES 2018
datatype
integer
string
integer
integer
real
Use
unique identification number
name of child
age of child in years
number of 2 kilometre runs completed
fastest time run
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Question
1(b)
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Cambridge O Level – Mark Scheme
PUBLISHED
535
October/November 2018
Answer
Many correct answers. 1 mark for each correct point (max 4).
Marks
4
Ensuring uniqueness e.g.
• Search list of previously stored identification numbers (1)
• To check it has not already been used. (1)
Calculation and addition of check digit
• Attempt at calculation of check digit from the first three digits // calculation from all four digits to obtain zero remainder
(1)
• Adding the calculated check digit as a fourth digit // confirming the check digit is valid. (1)
1(c)
© UCLES 2018
Any four from:
1 Initialisation//Setting up array for race times for this race
2 Loop for all runners
3 Input ID
4 Check for valid ID number
5 Input start time and finish time
6 Calculate run time
7 Store run time in suitable array//Use ID index to store run time in appropriate position
8 Store ID in suitable array//Find index for runner
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Question
1(c)
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Answer
Sample answer:
Counter ← 1
Found ← FALSE
WHILE NOT Found = TRUE
OUTPUT "Please enter ID number use 9999 to finish "
INPUT ParkrunID
Search ← 1
REPEAT
IF ParkrunID = IdNumber[search] THEN Found TRUE
Search ← Search + 1
UNTIL Search = 21 OR Found = TRUE
ENDWHILE
RunnerID[Counter] ← ParkRunID
WHILE ParkRunID <> 9999
INPUT StartTime
INPUT FinishTime
RunnerTime[Counter] ← FinishTime – StartTime
Counter ← Counter + 1
Found ← FALSE
WHILE NOT Found = TRUE
OUTPUT "Please enter ID number (use 9999 to finish) "
INPUT ParkrunID
Search ← 1
REPEAT
IF ParkrunID = IdNumber[Search] THEN Found ← TRUE
Search ← Search + 1
UNTIL Search = 21 OR Found = TRUE
ENDWHILE
RunnerID[Counter] ← ParkRunID
ENDWHILE
Page 6 of 11
October/November 2018
Marks
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
537
Question
1(d)
Answer
1 mark for each correct point (max 4).
Marks
4
Explanation:
1 Search the results for this park run
2 Separate check for each age range
3 If time recorded is faster
4
store new fastest time
5
store the ID/Name for the runner
6 Use ID number/Index to look up name after all runners have been searched
7 Output name and fastest time
Programming statements may be used but must be fully explained.
© UCLES 2018
October/November 2018
Page 7 of 11
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
538
Question
Answer
October/November 2018
Marks
Section B
2(a)
Any five from:
1 Use of correct variables
2 Input 3 numbers
3 Check all 3 input numbers are different
4 Attempt to find the largest two numbers input
5 Correctly finding the largest two numbers
6 Multiply their two largest numbers together and assign to variable
7 Output the result of the multiplication
5
Sample answer:
REPEAT
OUTPUT "Enter three different numbers"
INPUT Number1, Number2, Number3
UNTIL Number1 <> Number2 AND Number2 <> Number3 AND Number3 <> Number1
IF Number3 < Number2 AND Number3 < Number1
THEN Answer ← Number1 * Number2
ENDIF
IF Number2 < Number3 AND Number2 < Number1
THEN Answer ← Number1 * Number3
ENDIF
IF Number1 < Number2 AND Number1 < Number3
THEN Answer ← Number2 * Number3
ENDIF
OUTPUT "Answer = ", Answer
2(b)
There are many correct answers. E.g.:
4
7, 7, 7
(1 mark)
should be rejected as numbers are equal (1 mark)
7, 8, 9
normal data answer should be 72
© UCLES 2018
(1 mark)
(1 mark)
Page 8 of 11
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2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
539
Question
3
Question
4
Answer
Marks
1 mark for each correct line (max 3)
Each box must have only one connection.
3
Answer
Marks
Answers must be given in context. There are many possible answers. E.g.:
Selection use of IF statement to check the values of the meter readings (1 mark)
IF Reading > 400 and Reading < 900 THEN …
(1 mark)
Repetition use of FOR loop to check all 2000 meter readings
FOR Meter = 1 TO 2000 … NEXT
© UCLES 2018
October/November 2018
Page 9 of 11
(1 mark)
(1 mark)
4
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
540
Question
5(a)
October/November 2018
Answer
Marks
Height
Depth
Chlorine
OK
OUTPUT
6
2.5
2
True
Pool OK to use
Height
Depth
Chlorine
OK
OUTPUT
4
3
1.5
True
Water too deep
6
False
Height
Depth
Chlorine
OK
OUTPUT
6
3.5
4
True
Water too deep
False
Too much chlorine add more water
1 mark for first 4 columns in each trace table (max 3)
1 mark for the output in each trace table (max 3)
5(b)
© UCLES 2018
Any one from:
Cannot add more water if the water is too deep
No validation e.g. allows a negative height/depth/amount of chlorine
Tells you to add chlorine when there is no water
Runs only once
Page 10 of 11
1
.
2210/22
Cambridge O Level – Mark Scheme
PUBLISHED
541
Question
6(a)
Answer
6(b)
4
Data type
Reference Number
Text
Size
Text
Type
Text/Boolean
Price in $
Number/Currency
1 mark per bullet:
•
•
•
© UCLES 2018
Marks
Many correct answers, an example is given. 1 mark for each correct row (max 4).
Field
October/November 2018
3
Incorrect field name for Reference Number
Incorrect criteria for Price in $ should be <
Type not checked
Page 11 of 11
.
542
Cambridge Assessment International Education
Cambridge Ordinary Level
COMPUTER SCIENCE
2210/12
Paper 1
October/November 2018
MARK SCHEME
Maximum Mark: 75
Published
This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the
examination. It shows the basis on which Examiners were instructed to award marks. It does not indicate the
details of the discussions that took place at an Examiners’ meeting before marking began, which would have
considered the acceptability of alternative answers.
Mark schemes should be read in conjunction with the question paper and the Principal Examiner Report for
Teachers.
Cambridge International will not enter into discussions about these mark schemes.
Cambridge International is publishing the mark schemes for the October/November 2018 series for most
Cambridge IGCSE™, Cambridge International A and AS Level components and some Cambridge O Level
components.
This document consists of 12 printed pages.
© UCLES 2018
[Turn over
2210/12
.
Cambridge O Level – Mark Scheme
PUBLISHED
543
Generic Marking Principles
October/November 2018
These general marking principles must be applied by all examiners when marking candidate answers. They should be applied alongside the
specific content of the mark scheme or generic level descriptors for a question. Each question paper and mark scheme will also comply with these
marking principles.
GENERIC MARKING PRINCIPLE 1:
Marks must be awarded in line with:
•
•
•
the specific content of the mark scheme or the generic level descriptors for the question
the specific skills defined in the mark scheme or in the generic level descriptors for the question
the standard of response required by a candidate as exemplified by the standardisation scripts.
GENERIC MARKING PRINCIPLE 2:
Marks awarded are always whole marks (not half marks, or other fractions).
GENERIC MARKING PRINCIPLE 3:
Marks must be awarded positively:
•
•
•
•
•
marks are awarded for correct/valid answers, as defined in the mark scheme. However, credit is given for valid answers which go beyond the
scope of the syllabus and mark scheme, referring to your Team Leader as appropriate
marks are awarded when candidates clearly demonstrate what they know and can do
marks are not deducted for errors
marks are not deducted for omissions
answers should only be judged on the quality of spelling, punctuation and grammar when these features are specifically assessed by the
question as indicated by the mark scheme. The meaning, however, should be unambiguous.
GENERIC MARKING PRINCIPLE 4:
Rules must be applied consistently e.g. in situations where candidates have not followed instructions or in the application of generic level
descriptors.
© UCLES 2018
Page 2 of 12
2210/12
GENERIC MARKING PRINCIPLE 5:
.
Cambridge O Level – Mark Scheme
PUBLISHED
544
October/November 2018
Marks should be awarded using the full range of marks defined in the mark scheme for the question (however; the use of the full mark range may
be limited according to the quality of the candidate responses seen).
GENERIC MARKING PRINCIPLE 6:
Marks awarded are based solely on the requirements as defined in the mark scheme. Marks should not be awarded with grade thresholds or
grade descriptors in mind.
© UCLES 2018
Page 3 of 12
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
545
Question
1(a)
Answer
1 mark for each correct 8-bit binary number
October/November 2018
Marks
3
66
0
1
0
0
0
0
1
0
85
0
1
0
1
0
1
0
1
83
0
1
0
1
0
0
1
1
1(b)(i)
1 mark for each correct hexadecimal number
4B
45
59
3
1(b)(ii)
Three from:
• (HTML) colour codes
• Error messages
• MAC addresses
• IP addresses
• Assembly language
• Memory dump
• Locations in memory
3
1(b)(iii)
Two from:
• Easier to read/write/understand (for humans)
• Easier to remember (for humans)
• Short way to represent binary // Uses less screen/display space
• Fewer errors made (in data transcription)
• Easier to debug (for humans)
2
© UCLES 2018
Page 4 of 12
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
546
Question
2(a)
October/November 2018
Answer
Marks
1 mark for each correct tick (9)
3
Statement
Stores the programs and data that are currently in use
RAM
(9)
ROM
(9)
9
Used to boot up the computer when power is turned on
9
Contents are retained when power is turned off
9
2(b)
Primary
1
2(c)
Two from:
• Non-volatile storage
• Storage that can be disconnected/removed from the computer
• Any suitable example
• Must be (physically) connected to computer to obtain stored data
• Used to store files as a backup
2
© UCLES 2018
Page 5 of 12
2210/12
.
Cambridge O Level – Mark Scheme
PUBLISHED
547
Question
3
© UCLES 2018
Answer
1 mark for each correct logic gate, with correct inputs.
October/November 2018
Marks
5
Page 6 of 12
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
548
Question
Answer
October/November 2018
Marks
4(a)
Three from:
• Malware
• Virus // No antivirus
• Denial of service
• Spyware // No antispyware
• Phishing // opening unknown links/emails
• Pharming // opening unknown links/emails (only award once for this alternative)
• Hacking/cracking/unauthorised access // No/weak password // No/weak firewall
• Downloading/Using unknown software
• Not updating software
• Physical issue e.g. computer/door left unlocked
3
4(b)
Four from:
• It examines/monitors/filters traffic into and out of a computer
• It allows a user to set criteria/rules for the traffic
• It checks whether the traffic meets the criteria/rules
• It blocks any traffic that does not meet the criteria/rules // Blocks unauthorised access
• It warns a user of any unauthorised software/access/unauthorised outgoing traffic
• It keeps a log of all traffic (that can be examined)
4
Question
Answer
Marks
5(a)(i)
2D/3D cutter
1
5(a)(ii)
Liquid crystal display // LCD
1
5(a)(iii)
Actuator
1
1 mark for each correct missing word, in the given order:
• interactive whiteboard
• inkjet
• thermal bubble
• laser
• rotating
5
5(b)
© UCLES 2018
Page 7 of 12
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
549
Question
6(a)
6(b)
© UCLES 2018
Answer
•
•
October/November 2018
Marks
2
Compiler
Interpreter
Four from:
• Closer to human language/English «
• « so it is easier/quicker to read/write/understand
• « so it is easier/quicker to debug the program
• « therefore, less likely to make errors
•
•
•
The program can be used on many different platforms «
« because it is written in source code
« because it is compiled into object code
•
•
They have built-in functions/libraries «
« this saves time when writing the program
•
•
Do not need to manipulate memory addresses directly «
« therefore, specialist knowledge of this is not required
•
•
Only need to learn a single language «
« as this can be used on many different computers
Page 8 of 12
4
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
550
Question
6(c)
October/November 2018
Answer
Marks
1 mark for each correct tick (9)
Computer code
3
High-level
language
(9)
Assembly
language
(9)
10110111
11001100
01011100
FOR X = 1 TO 10
PRINT X
NEXT X
9
9
INP X
STA X
LDA Y
© UCLES 2018
Machine
code
(9)
9
Page 9 of 12
.
2210/12
Cambridge O Level – Mark Scheme
PUBLISHED
551
Question
7
Answer
1 mark for each correct line (to a maximum of 5)
Browser
© UCLES 2018
October/November 2018
Marks
5
A program that allows a user to view
webpages
Internet Service Provider
(ISP)
The main protocol that governs the
transmission of data using the Internet
Hypertext Transfer Protocol
(HTTP)
The website address that is typed into
the address bar
Uniform Resource Locator
(URL)
An address given to each device on a
network. It is provided by the network
MAC address
A unique address given to a device on
a network. It is provided by the
manufacturer
IP address
A company that provides a connection
to access the Internet
Page 10 of 12
2210/12
.
Cambridge O Level – Mark Scheme
PUBLISHED
552
Question
8
Answer
Four from:
• Used to attend to certain tasks/issues
• Used to make sure that vital tasks are dealt with immediately
• The interrupt/signal tells the CPU/processor (that its attention is required)
• A signal that can be sent from a device (attached to the computer)
• A signal that can be sent from software (installed on the computer)
• The interrupt will cause the OS/current process to pause
• The OS/CPU/ISR will service/handle the interrupt
• They have different levels of priority
• After the interrupt is serviced, the (previous) process is continued
• It enables multi-tasking to be carried out on a computer
• A valid example of an interrupt e.g. ‘out of paper’ message for a printer
Question
Answer
October/November 2018
Marks
4
Marks
9(a)(i)
Two from:
• Data is transmitted one bit at a time
• Data is transmitted using a single wire
• Bits arrive in order/sequence
2
9(a)(ii)
Two from:
• Data is transmitted multiple bits at a time/simultaneously
• Data is transmitted using multiple wires
• Bits may arrive out of sequence/skewed (and are reordered)
2
9(a)(iii)
1 mark for each:
• Data is transmitted in both directions
• « at the same time/simultaneously
2
© UCLES 2018
Page 11 of 12
2210/12
.
Cambridge O Level – Mark Scheme
PUBLISHED
553
Question
9(b)
October/November 2018
Answer
Maximum of three marks per error detection method.
1 mark for naming the method, 2 marks for describing it.
Parity (check)
• Odd or even parity can be used
• Bits are added together // 1 bits are counted
• Parity bit added (depending on parity set)
• Parity checked on receipt
• If parity bit is incorrect an error is detected
Marks
9
Checksum
• Calculation performed on data (to get the checksum)
• Checksum sent with data
• Checksum recalculated after transmission
• Comparison made between checksum before and checksum after transmission
• Error detected if checksums are different
Automatic repeat request (ARQ)
• Uses acknowledgement and timeout
• Request is sent (with data) requiring acknowledgement
• If no response/acknowledgment within certain time frame data package is resent
• When data received contains an error a request is sent (automatically) to resend the data
• The resend request is repeatedly sent until packet is received error free/limit is reached/acknowledgement received
Question
10
© UCLES 2018
Answer
Five from:
• The sensor sends data to the microprocessor
• The analogue data is converted to digital (using ADC)
• The microprocessor compares the reading to the set range/stored values/stored data (6 to 8) «
– « If the reading is >8 or <6 / outside range «
o « the microprocessor sends a signal to output the alert
• The process is continuous/repeated
Page 12 of 12
Marks
5