PROVISIONAL MARKING KEY

Section A
1. A 6. C 11.A 16.B
2. A 7. C 12.A 17.C
3. D 8. C 13.B 18.D
4. C 9. A 14.B 19.D
5. D 10.C 15.C 20.B

Section B
21. a. What is a computer
A computer is an electronic device that accepts data under the control of
a programme process it and produce an output.1
Or
A computer is an electronic device that processes data to information1

b. What was the main use of the following computers

i. Napier’s Bones: for performing multiplication1 and division1
ii. First-generation computers: computation of very large mathematical 1
and scientific1 figures.
Or
to make calculation for construction of a hydrogen bomb1.
1

22. a. Define a programme

a programme is a set of instructions that guides a computer on what to
do.1
b. Differentiate the following
i. Data and information

Data are raw facts that do not give meaning to the user1 while
information is processed data which more meaningful to the user1

ii. Communication technology and information technology

CT is the use of devices and communication channels to transmit
information1 while IT is the use of hardware, software and their
technologies to collect, organise, process, secure, store, exchange or
disseminate information1
23. a. What does ASCII stand for?
 American Standard Code for Information Interchange
b. Explain the concept of character set?
A character set converts a binary code/number to its equivalent human
readable form1and vice versa1
24. Figure 1 is a diagram showing a computer system.

C
a. Identify parts labelled B and D
B: keyboard1
D: system unit1
b. State the functions of part labelled C and A
C: Any 1
- Controls cursor movement on the screen1
- For selecting 1
- Scrolling1
- Opening context menu1

A: displays output of the computer1

25. a. Why are microcomputers called personal computers?

Because they are designed for a single user/person at a time1
b. Explain One advantage of using supercomputers for scientific research?
Any one
 - High Processing Power1, Supercomputers can perform billions or
trillions of calculations per second, enabling researchers to tackle
complex problems that require extensive computational resources1.
- Large-Scale Data Analysis1 Supercomputers can handle massive
datasets,
26. a. Convert 200bits to bytes
8 bits = 1 byte1
200 bits
200bits = 8 bits x 1byte 1
= 25bytes1
b. How many bytes are there in 3 megabytes
1 mb = 1024 x 1024 bytes or 1 mb = 1000 x 1000bytes1
3mb = 3 x 1024 x 1024bytes or 3 x 1000 x 1000bytes1
= 3145728bytes or 3 000 0000bytes1
27. a. State any three examples of keying devices
any three
- Traditional keyboard1
- Flexible keyboard1
- Ergonomic keyboard1
- Keypad1
- Braille keyboard1
b. Describe a digitizer
this is an input device that you can use to draw an image using a stylus.1the
drawn image appears on the computer screen1
c. List any two examples of softcopy output devices
- Monitors1
- Projectors1
28. a. State three examples of storage devices
any three
- Floppy disk1
- Memory card1
- Flash disk1
- Hard disk1
- CD/DVD 1
- Solid state drive1
- Magnetic tapes1
b. what is the difference between static MROM and dynamic EPROM
 MROM once the content is written on it by the manufacturer it cannot be
changed while EPROM its contents can be erased by exposing it to ultra
violet light and reprogrammed for another use
29. a. State any three causes of software and data loss.
any three
- Accidental deletion1
- Malicious deletion1
- Accidental media format1
- Accidental damage1
- Natural disaster1
- Power failure1
- Hardware failure1
- Software failure1
- Vandalism1
b. Describe how you can protect the computer hardware from power surge
by using UPS1, UPS provide stable power supply required by the computer1, it
regulates fluctuations in power being supplied to the required amount.1
c. Why are communication devices considered indispensable in today’s
world?
Today we live in an interconnected world where communication channels
have become a vital part of our day-to-day lives1. For this reason, a
computer without communication devices is seen as least useful 1
30. Explain two ways on how you can clean files affected by viruses
- Using antivirus software1 – antivirus software detects and removes the
virus from your computer1.
- Deleting the affected files – another way is by manually deleting the
infected files.

Section C
31.a. Briefly explain how the following affect the computer
i. Liquids
Any one
- Short Circuits:1 When liquids spill onto computer components, they
can create electrical shorts, disrupting the normal flow of electricity. 1
 - Rusting - contact
ii. Dust particles
- They may increase friction and wear of movable parts. They may also
cause the disk to crash.
iii. Temperature
- high temperature affects proper functioning of computer chips
- when you expose sunlight to storage devices they may crash
b. Differentiate between general purpose and special purpose computers
with the aid of examples?
A general purpose computer is a computer that is designed to carry out
many different task1 for example a laptop, desktop, smartphones1 while
special purpose computers are designed to carry out a single task1, for
example calculators, groundphones1
32.a. Describe three precautions you would take to avoid damaging the hard
disk
any three
- Handle the Hard Disk Carefully: Hard disks are delicate devices and can be
easily damaged by physical shock or impact. Therefore, it's important to
handle the hard disk with care and avoid dropping, hitting or jarring it.
Always hold the hard disk by the edges and avoid touching the exposed
circuitry or connectors.
- Maintain Proper Operating Conditions: Hard disks generate heat during
operation, and excessive heat can damage the disk. Make sure that the hard
disk is installed in a well-ventilated area, away from direct sunlight, and
other sources of heat. You can also use cooling fans or other cooling devices
to keep the hard disk temperature under control.
- Protect Against Electrical Surges: Electrical surges and power spikes can
cause damage to electronic devices, including hard disks. To prevent this, use
a surge protector to protect the hard disk from power surges. You can also
use an uninterruptible power supply (UPS) to provide backup power and
protect the hard disk in case of a power outage or surge.
- Keep the Hard Disk Clean: Dust and other particles can accumulate on the
hard disk's surface, which can cause the head to crash and damage the disk.
 Keep the hard disk clean by wiping it with a soft, lint-free cloth or using a
specialized cleaning kit.
- Avoid Magnetic Fields: Strong magnetic fields can erase the data on the hard
disk or damage the disk itself. Keep the hard disk away from sources of
strong magnetic fields, such as speakers, transformers, or large motors.
- Eject the Hard Disk Properly: When disconnecting the hard disk from a
computer, always eject it properly by clicking on the "Eject" button or using
the operating system's "Safely Remove Hardware" feature. This ensures that
all data has been written to the disk and that the disk is not in use when it's
disconnected.
b. Describe any two functional elements of a CPU
any two
- Control Unit1 is the part of the CPU that is responsible for coordinating all
the processing activities in the CPU, input, storage and output operations1
- Arithmetic and Logic Unit1 is the part of the CPU that is responsible for
carrying out all arithmetic and logic operations1.
- Main memory1 is also called Primary Storage because it is directly accessed
by the processor, it serves as temporary storage for data and instructions
that the CPU needs to access quickly during processing1.
33. Discuss how computers are used in any five different fields
Any five
- In super markets1 Computers are used to monitor and control stock. The
system keeps on account what is in stock and what is out of stock that
needs reordering1.
- In offices1 Some of the uses of computers in offices are sending emails,
writing letters, scheduling meetings and collaborating with co-workers
and clients1.
- In hospitals1, computers are used to keep, maintain and access patient’s
records1.
- In education1 computer are used for keeping school records and as
teaching aid1.
- Law enforcement1 Computers are used to keep fingerprints, images and
other identification details1.
- Entertainment1 you can play games, listen to music or watch movies on
the computer1.