1.
Computer System
John is an architect. He uses a computer to prepare architectural plans, to
communicate with his friends through the telephone lines and to search for
information through Internet. He decides to buy a new computer.
Below is a table comparing two types of microcomputer:
Type
Notebook
Desktop
200MHz
300MHz
Main Memory
64MB
128MB
Hard Disk
10GB
40GB
Monitor
12" LCD
17" VGA
Modem
--
56 Kbps
$10120
$7000
CPU
Price
(a) After considering his needs, John chooses to buy the Desktop. State TWO ways
in which the Desktop can meet the John's needs.
It has a modem for accessing Internet. The Desktop has a larger display
area which is better for preparing architectural plans.
(b) Name ONE type of output device that John should add to the Desktop if he
wants to produce hardcopy of poster-size architectural drawings.
_Graph Plotter_________________________________________________
(c) Name ONE type of input device that John should add if he wants to input photo
to the computer.
2.
__Scanner____________________________________________________
Many supermarkets install bar code readers at cashier counters to read the bar code
of each item. Besides a reader, a keyboard is also installed as an input device.
(a) Give ONE advantage of not marking prices on individual items.
The prices are stored in the computer and they can be changed easily.
(b) Describe ONE situations when a keyboard, instead of the bar code reader, must
be used to enter a bar code number.
If the bar code on a product is damaged, the bar code number can be
inputted through the keyboard.
(c) Give TWO advantages of using bar code scanners in supermarkets.
Faster services, higher accuracy.
Computer Network
(Solution is appended at the end of the doc.)
1. Name three common network topologies for LAN and brief describe their
connections.
2. What hardware must be used for two computers communicating through a telephone
line? Also describe why it must be used.
3. Name three network media and compare their cost and quality for networking.
4. Give one example of a transmission medium that is a direct cable connection and
one example of transmission medium that is not a direct cable connection. Also state
one advantage and one disadvantage of direct cable connection over others.
5.
6.
7.
Give two advantages of network over standalone computer.
What is a protocol?
What is the function of a router?
8.
What is the function of a firewall?
Suggested Solution.
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8.
Star : each computer is connected to a central computer by a cable.
Bus : All computers are connected to a cable .
Ring : A network cable passes from one computer to another until all computers are
interconnected in the form of a ring.
A modem. Since telephone line carries analog signal only, digital signal of computer
must be converted into analog signal. At the receiving end, the analog signal is
reconverted back into digital signal for the computer at the other end to receive.
Twisted-pair wire, coaxial cable and optical fibre.
Cost: optical fibre > coaxial cable > Twisted-pair wire
Quality: optical fibre > coaxial cable > Twisted-pair wire
Optical fibre is a direct cable connection transmission medium while microwave is
not. The transmission speed of direct cable connection is generally higher than a
wireless connection. However, cable connection is difficult to setup and not flexible
to connect.
Sharing resources and communication with others.
A set of rules for governing the transmission and receipt of data.
A router is used to connection different networks.
A firewall is a system or combination of systems that helps to prevent outsiders from
obtaining unauthorised access to internal information resources
The Computer System
1. State one advantage and one disadvantage of using floppy disk over a hard disk as a
backing store.
2. State one advantage and one disadvantage of using monitor over a printer as an output
device.
3. Although magnetic disk is faster than magnetic tape in accessing data, magnetic is
still used nowadays for storage. Explain why.
4. Suggest one input device and one output device for a blind computer user and explain
why they are suitable.
5. What are the advantages to the performance of a computer if the amount of RAM is
increased?
6. In order to construct a school network, both optical fibre and twisted wire are used.
Explain what they are different and how they are arranged in a school network.
7. Explain why it is necessary to use modem in computer communications through
telephone lines.
8. Give two advantages and two disadvantages of networking.
9. State one advantage and one disadvantage of choosing a custom-made software over a
packaged software.
10. List two examples of utility program.
The Computer System – Suggested Solution
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3.
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5.
6.
Advantage: Removable
Disadvantage: Small capacity
Advantage: Instant output
Disadvantage: Temporary
Magnetic tape is a cheaper medium for backup
Input device: Keyboard. Although a blind user cannot see, he can touch.
Output device: Speaker. Although a blind user cannot see, he can hear.
Increase the working space for the computer. So more jobs can be done at the same
time.
Optical fibre transmits optical signal. It is not influenced by electronic noise and it is
suitable for long distance communication. Twisted-pair transmits electrical signal. It
is easier influenced by electronic noise. It can only be used for short distance
communication. In a school network, optical fibre is used for communication
between floors while twisted-pair is used for communication in the same floor.
7. Telephone line allows analog signal to go through while computer can only process
digital signal. So a modem is necessary to convert between analog signal and digital
signal.
8. Advantages: Sharing resources, communication
Disadvantages: Easier for spreading computer virus, risk of hacking.
9. Advantage: Fit your needs.
Disadvantage: Expensive.
10. Disk scanning, disk backup.
Computer Applications – The Computer System ( Quiz)
1.
Draw a diagram to show the relationship of the major hardware components. In your
diagram, you should indicate the data flow and the control flow.
2. Explain how the following changes can improve the efficiency of a computer.
(a) Increase the RAM size;
(b) Increase the clock rate of CPU;
(c) Change the 56k modem to broadband modem.
3. Give one suitable application for each of the following device.
(a) Image scanner;
(b) Bar code scanner;
(c) Magnetic Ink Character Reader;
(d) Optical Mark Reader.
4. Give one advantage and one disadvantage of output data on a printer over a VDU.
5. The access speed of a magnetic tape is significantly lower than that of a magnetic disk.
However, it is still widely used in servers. Explain.
6. Give one advantage and one disadvantage of choosing a custom-made software over a
packaged software.
7. Browser, Unix, anti-virus program, modem, plotter, computer games, router, editor, word
processing program, image scanner.
Classify the above items into (1) Hardware, (2) System software or (3) Application software.
8. Give one difference between CD-ROM and CD-R.
9. EEPROM (Electrically erasable programmable read-only memory) is widely used to replace
ROM. Give one advantage and one disadvantage of using EEPROM over ROM to store
system program.
10. Touch screen is used in kiosk to replace keyboard. Give one advantage and one disadvantage
for such arrangement.
Computer Applications – The Computer System (Quiz) – Marking Reference
1.
ALU
Input Device
Output Device
CU
Data flow
Main Memory
Control flow
Backing Store
Data flow (1)
2.
(b)
(c)
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10.
Control flow(1)
Components (1)
(a) Increase the working space for the computer. So more jobs can be done at the
same time. (1)
Increase the processing speed of the CPU. (1)
Increase the transfer rate when accessing Internet. (1)
(a) Scan photos into the computer. (1)
(b) Scan bar code of product in supermarket. (1)
(c) Bank cheque processing. (1)
(d) Multiple-choice worksheet marking. (1)
Advantage: Permanent output(1)
Disadvantage: Not instant (1)
Magnetic tape is a cheaper medium for backup. (2)
Advantage: Fit your needs. (1)
Disadvantage: Expensive. (1)
Hardware: Modem, plotter, router, image scanner
System Software: Unix, anti-virus program, editor
Application Software: Browser, computer games, word processing program
CD-ROM: Read-only
CD-R: Write once, read many
Advantage: The content can be upgraded.
Disadvantage: It may be infected with computer virus.
Advantage: Save space
Disadvantage: Not suitable for typing