Mark Scheme
Computer Studies Term 1 Examination
2014-2015
Secondary 3
1
(a) People needs computer to make their job easier and produce a better quality
of work.
What is meant by a computer?
A computer is an electronic device, operating under the control of instructions
stored in its own memory
[2]
(b) There are many computer devices that we know and this can enhance the
functionality of computer, such as input and output devices.
(i)
What is meant by input devices?
Input device is hardware component that allows users to enter data and
instructions into a computer
[2]
(ii)
Mention two examples of input devices and its function.
Input device: keyboard
Function: to input data into computer, select data
………………………………………………….………………...........…………………...
Input device: microphone
Function: to input voice, sound, music into computer
………………………………………………….………………...........…………………... [4]
(iii)
Input devices are classified into two main categories, “manual input
devices” and automatic input devices (automatic data capture).
Explain the meaning of both and give example for each.
Manual input device is: the device that requires human interactions to
make it work.
Example Joystick
[2]
Automatic input device is: the device that does not need human
interactions to make it work as its already pre-configured by humans.
Example: sensors
[2]
2
Write the defnition of the following terms and justify your answer by explaining the
use of each.
(a) Concept keyboard
Is a special input device that functions like a touch-screen keyboard that
contatins menu to input.
e.g: the one used at a restaurant cashier
[2]
(b) Biometric input device
Is a device that can sense / read physical quantities of human to input into
computers.
e.g: finger-print scanner
[2]
(c) OMR
Optical mark reader: is another input device that can read a hands-drawn
marks such as small circles or rectangles in the filling-form or in multiple choice
exams. e.g: OMR that is used to mark multiple choice question.
[2]
(d) OCR
Optical character reader: It is software that scans documents containing texts
and converts them into documents that can be edited.
[2]
2
(e) MICR
Magnetic ink character readers is a device that is used to read text printed
using a magnetised ink. e.g: bank cheque reader
[2]
3
(a) What is meant by sensor and what is it used for?
Is a device that detects or measures a physical property and records, indicates,
or otherwise responds to it. e.g: temperature sensor
[2]
(b) Mention two examples of physical quantities that can be captured by sensor.
-
4
Humidity
Temperature
Light insensity
Mass
Length
Etc.
[2]
(a) What is output device?
Is a device or a part of computer system that is used to output data that has
been previously entered into a computer.
[2]
(b) Give two examples of output devices and explain how they work.
-
Monitor: display data that is being processed in the form of text and
graphics
-
Speaker: output data that is being processed in the form of sounds or voices [2]
3
(c) There are many types of printer people use in printing agency or publishing
industry.
Mention three types of printer that you know and explain what is the specific use
of each printer.
5
-
Laser printers
Use powdered ink, called toner that is fused onto paper by heat and
pressure, good for printing a large number of papers because it is fast.
-
Ink-jet printers
Use ink that is processed by heating it as it flows through a set of tiny nozzles,
good for a home/personal/small office printing.
-
Dot matrix printers
Use a carbon ribbon that is hit by print head that is leaving an imprint on the
paper, good for printing documents that requires a multiple copies as it can [3]
be used for the carbonised paper.
(a) What is the difference between storage device and storage medium?
Give example for each.
-
Storage device is the device used to read data/information stored in a
storage medium. E.g: CD-ROM drive.
-
Storage medium is a medium where we store data/information for future use.
[2]
E.g: a CD-ROM
(b) What does it mean by the term ‘Access time’ that people use regarding storing
data in a storage medium?
The amount of time that takes a storage device to locate an item on a storage
medium.
For a hard disk, the access time is normally in milliseconds (thousandth of a
second). For solid state memory such as RAM it is in nanoseconds (thousand
[2]
millionth of a second).
(c) Flash memory chips are a type of solid state media and contain no moving
parts. Solid state drives (SSDs) have several advantages over magnetic hard
disks.
Mention three of them.
-
Faster access time
Smaller in size
More easy in maintenance
More stabil in use
[3]
4
(d) Credit card, ATM card, and E-toll card also function like a storage that contains
information inside.
Mention three possible information can be stored in a credit card.
-
ID number of cards
-
Authorised bank
-
Expiracy date of cards
[3]
6
For each of the following five groups of hardware items, write down a computer
application that would need those items.
List of hardware items
7
Application
webcam, microphone,
speakers
Video conferencing
barcode reader, POS,
terminal
Record the transactions
pressure sensor, ADC, lights,
siren
Alarm
data gloves, data goggles
Simulation
light pen, plotter, 3D printer
Printing
[5]
(a) What does the term 'bit' mean in computing context?
Is a short form of ‘Binary digit’, a smallest measurement of data.
[1]
(b) How are bits represented in an operating computing?
Every single bit is represented in a form of binary number, either 1 or 0.
One byte contains 8 bits.
E.g: 11001011, this is one byte
[2]
5
(c) Why do computers use the binary number system rather than the decimal
system?
-
Because binary digits can be processed quicker than decimal
-
The cost to build a binary base system is cheaper than to build a denary
(decimal) system
8
[2]
Convert the following binary numbers into decimal numbers.
Write down the calculation processes for the evidence.
(a) 11000101
197
The draft that shows the cprocess of calculating must be provided.
[2]
(b) 10111011
187
The draft that shows the cprocess of calculating must be provided.
[2]
9
Convert the following decimal numbers into binary numbers.
Write down the calculation processes for the evidence.
(a) 215
11010111
The draft that shows the cprocess of calculating must be provided.
[2]
6
(b) 571
111111011
The draft that shows the cprocess of calculating must be provided.
[2]
10 Convert the following hexadecimal patterns into decimal numbers.
Write down the calculation processes for the evidence.
(a) 78FC
12 x 1
15 x 16
8 x 256
7 x 4096
30972
[2]
(b) 12D
13 x 1
2 x 16
1 x 256
301
[2]
11 Convert the following decimal numbers into hexadecimal patterns.
Write down the calculation processes for the evidence.
(a) 1200
4B0
The draft that shows the cprocess of calculating must be provided.
[2]
7
(b) 684
2AC
The draft that shows the cprocess of calculating must be provided.
[2]
12 Convert the following binary numbers into hexadecimal patterns.
Write down the calculation processes for the evidence.
(a) 11010111
13
7
D7
[2]
(b) 100011100101
8
14
5
8E5
[2]
13 Convert the following hexadecimal patterns into binary numbers
Write down the calculation processes for the evidence.
(a) 35F
0011
0101
1111
001101011111
[2]
8
(b) 7CB
0111
1100
1011
011111001011
[2]
14 A digital alarm clock is contolled 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
8
:
3
5
is represented by:
0
0
0
0
1
0
0
0
0
0
1
1
0
1
0
1
(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
1
6
:
4
9
[2]
9
(b) What would be stored in the 4-digit binary codes if the clock display time was:
1
7
:
2
9
0
0
0
1
0
1
1
1
0
0
1
0
1
0
0
1
[4]
(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.
Read the time continuously
Compare the time with the pre-set time
If time read = pre-set time
Set alarm on
[2]
End of Paper
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