S.P.8 KCSE COMPUTER STUDIES PAPER 1 PAST QUESTIONS AND ANSWERS

SAMPLE PAPER 8

COMPUTER STUDIES PAPER 1

451/1

SECTION A (40marks)

1. Explain the following terms as used in information Technology with reference

to software purchase:-

i) User friendliness ( 1mk )

Refers to how easy the software is to use for the user.

ii) Authenticity ( 1mk )

The genuinessess , validity and / or legitimacy of the software.

2. In system development testing is one of the critical stages. Give three reasons

why the testing phrase is critical to the systems developer. ( 3mks )

• Helps to ensure that the logical and physical designs and environment are to the users satisfaction
• Helps to detect and correct errors.
• Gives proof to those skeptical about the working of the system
• Helps to establish how the system works under various conditions allowing for full description of the system capabilities.

3. Give three ways in which a magnetic tape differs from a magnetic disk

Magnetic disk Magnetic tape

-Tracks are concentric – Tracks are parallel and located lengthwise

-Move only in one play direction – Move in two directions( forward and

Backwards)

– Do not come in control with the read – Comes in contact with the read/ write

/ write head heed

– Have shorter access time – Have longer access time

– Data accessed by a number of methods – Data accessed only by serial method.

4. Name the three components of a spreadsheet ( 3mks)

– Database

– Graphs

– Worksheet

5. i) What is a page header ( 1mk)

• This are the words at the top of every page of document just above the page margin

ii) Differentiate between a page margin and a page border. ( 1mk )

6. State any two differences between function keys and special keys of a keyboard.

( 2mks )

Function keys Special keys

– Normally used single to execute a task. – Normally used in combination with other

Keys the execute a task.

– Initiate frequently done task to occur – Give special instructions to the computer.

7. i) Give any two differences between margin guides and column guides as used

in desktop publishing ( 2mks)

– Column guides help to divide the pages into columns that make the publication look more organized and are witin a page, a normally pink coloured while margin guides are around the edges of the printable page and are normally blue in colour.

ii) what does the gutter in a word processor mean in relation to column settings? ( 1mk)

8. State any three advantage of using microwaves to transmit data. ( 3mks)

• Operate at a high speed
• Have a huge transmission capacity
• Are less prone to transmission errors
• Are capable of transmitting both digital and analogue signals

1. Name any three methods that can be used to test a program of errors (3mks)
   

• Desk checking ( Dry- run )
• Using debugging utilities
• Using test data.

10. Give any three characteristics of systems ( 3mks )

• Holistic
• Subsystems
• Boundary and environment
• Purpose
• Process
• Syetm entropy
• Inputs and outputs
• Open and closed system
• Control

11. Why is a computer referred to as an electronic device ( 1mk)

It utilizes electronic signals to process information

12. Why is a mobile phone regarded to be a computer ( 3mks )

• electronic device
• having inputs / output device
• programmable
• process date at high speed.

1. State any three reason why computers are a much more preferred machine to use
   

   in an office and business than other office machines. ( 3mks )

• computers process data faster
• computers are more accurate
• computers are more efficient ( they utilize minimum resources to process data)

14. State any three factors to consider when preparing a computer laboratory ( 3mks)

• security of programs and other resources
• reliability of the ( source of ) power
• the number of computers to be installed and available floor space
• the maximum number of users that the laboratory can accommodate.

15. state any two functions of a UPS ( 2mks )

• supply power to computers when power abruptly fails temporarily
• clean power to computers

SECTION B

16.a) i) State any two advantage of low level languages. ( 2mks )

• no translation
• processor execute them faster
• are stable and hardly crash down once written

ii) Explain in the following terms as used in high level languages.

Capsulation ( 1mk)

– Having data and functions that operate on the data within an object

Inheritance ( 1mk )

• child module based on parent modules takes on all features of the parent

module.

iii) Give any two examples of fouth generation languages. ( 2mks )

Visual basic, delphi pascal, visual COBOL,

1. Draw a flow chart that would be used to design a program that would evaluate the

value of F using the formula F = (5mks)

 Start (1mk)

(1mk)

Enter f1 = f₁, f₂ (1mk)

(1mk)

F = = f₁ + f₂

f₁ + f₂

 Out put F (1mk)

Stop logic (1mk)

1. From the flow chart developed in part ( b) above write a pseudocode to do the same

task as the flow chart ( 4mks )

Begin

Enter the values of f₁ and f₂ (1mk)

Calculate F

(1mk) F = f₁ + f₂ (1mk)

f₁ f₂

Output F – (1mk)

end

17. a) Explain the following computer crime terminologies below

 i) Hacking ( 1mk )

– Is breaking into a computer system to look at data, copy or modify data to which the person has no authority to access.

ii) Tapping ( 1mk )

– Getting access to data while in transmission

iii) Cracking ( 1mk)

– Is establishing of week access points in a software by use of guess work or otherwise but normally the cracker has some idea about the system securities.

iv) Piracy ( 1mk)

Making copies of copy righted software / data.

1. Fraud
   

   – Use of computers to conceal information or cheat other users with the intention of making a gain.

iv) Sabotage ( 1mk )

– The illegal destruction of data and information with the aim of cripping service delivery or causing loss to a firm.

 vii) Alteration ( 1mk)

Changing of data / information without permission with the aim of gaining or misinforming the authorized users.

b) Piracy is the worst computer crime that is scaring software developers out of their wits. Suggest any ways that can be instituted to reduce to reduce piracy ( 4mks )

• Enact laws that protect developers of software against piracy
• Make software cheap enough to increase affordability
• Use licenses and certificates to identify originals
• Set installation passwords that deter illegal installation of software
• create install once software.

c) State any four measures that can be taken to detect, prevent computer crimes and

seal security loopholes. ( 4mks )

– Audit trail

– Data encryption

– Log files

– Firewalls.

18. a) Network software comes in two main categories. Name them ( 2mks )

• Network operating system
• Network protocol

b) ( i) state any five unique network operating system software functions (5mk)

– Provides access to network resources

– Enable nodes to communicate with each other more efficiently

– Supports network services like network card drivers and protocols

– Implementats network security features.

ii) Name any two network operating systems ( 2mks)

windows NT, linux , Novell, windows 2000, windows 2003, unix.

c) Explain the following advantages of networking

i) Sharing of resources ( 2mks)

The resources include data / information, files printers, software etc.

• Users do not need to transfer data via removable media but sort straight saving on cost.
• Centralized access to data / information leads to less time wastage hence greeter productivity.

ii) Distributed facilities ( 2mks )

• The failure of the central computer does not affect the operations of other terminals
• Processing load is shared equally hence no time wastage and high quality productivity.

iii) Reliability ( 2mks )

• Data can be transferred with minimum error from source to destination
• In use one computer breaks, users can still access data / information from the other computers using another computer using another computer on the network.

19.a) Complete the table below that classifies errors that influence the accuracy of

data input and information output into / from a computer system ( 5mks )

 ERRORS

TRANSCRIPTION COMPUTATIONAL ALUOROTHMIC

ERRORS

TRANSCRIPTION MISREADING ROUDING OFF OVERFLOW TRUNCATION

 ERRORS

b) Explain what data integrity is by clearly describing its measures ( 7mks )

It is the accuracy and completeness of data entered and information received from on information system.

It is measured by:-

1. Accuracy : how close an approximation is to the actual value.
2. timeliness : deals with being given at the right time
3. Relevance: refer to entered data being pertinent to the processing needs at hand and meeting the requirements of the process cycle.

c) State any three advantages of files using sequential file organization method

• Approach is simple to understand
• Locating a record requires only the record key therefore fast.
• Efficient and economical if the activity rate is high.
• Relatively in expensive input / output media and devices may be used.

20. a) A shopkeeper of a small shop at manga has bought a desktop computer to assist him in performing his business activities. He has been advised that before he can use it to work he has to install it with an operating system. State any six factors to consider when choosing the operating system ( 6mks )

1. Hardware configurations ( memory size, type of processor; speed )

1. Basic design of the computer e.g IBM or IBM compatible or apple
2. Applications intended for the computer
3. User friendliness or human computer interface
4. Availability is the market
5. Lost
6. Reliability

b) With reference to disk management explain what is meant by the terms below.

i) Formatting ( 1mk)

– Preparing disks for data storage by creating sectors and tracks on the disk surface.

ii) Defragmentation ( 1mk)

– The rearrangement of scattered files on a storage media in order to speed

up access to files.

iii) Disk partitioning ( 1mk)

– The process of dividing a large physical disk into two or more portions / logical drives or volumes.

 c) Give any two reasons that may make the shopkeeper to partition the computer disk( 2mks)

• In order to install more than one operating system on the same disk.
• In order to be able to make back up on the same disk.

1. The shopkeeper one day switched on the computer and experienced a number of problems with windows operating system that he had installed. The problems included failure to load the operating system during the booting. After several trials of switching on the computer booting, it hang so often alongside abnormal restarting. State any four possible causes for the computer’s behaviour. (4mk)

• Hardware conflict or incompatibility possibility due to interrupt requests or missing device drivers.
• Possibility of a problem in the installation process
• Problem with hard disk boot sector due to damage or virus attack
• Insufficient memory
• Corrupted system windows registry.

SAMPLE PAPER 8

COMPUTER STUDIES PAPER 1

451/1

1. What do you understand by the following types of memory?

i. Mask read only memory

ii. Erasable programmable read only memory (EPROM)

(2mks)

2 State one function of the central processing unit (1mk)

3 a) what is a low level programming language. (1mk)

 b) How does it differ from a high level programming language. (1mk)

4 a) State two advantages of voice/speech input? (2mks)

b) List down two common ports on a computer system. (2mks)

5 a) What is the difference between character based operating system and graphical user interface operating system (2mks)

b) State two categories of input devices (2mks)

6 List down two factors to be considered when selecting an input device (2mks)

7 List down at least two precaution necessary in a computer laboratory (2mks)

8. The diagram bellow shows coded data that could be input into a computer

a) What is the name of the above method of input (1 mk)

b) Where would the above method of input be applied? (1 mk)

c) For the application you have given in the above question, state two items of

information this type of input may represent. (2 Mks)

9. a) Define the term variables as used in programming (Imk)

b) Explain why variables are important in a programme (2mks)

10. Differentiate between baseband and broadband signals as applied to data transmission

(2mks)

11. By using two compliment work out 31₁₀ – 17₁₀ in binary form.

Show your calculations clearly. (2mks)

12 Write brief notes to the following type of errors

i. Algorithmic errors.

ii). Transposition errors (2mks)

13 What is an Internet Service Provider (1SP) (2mks)

14 a) What is word wrap as used in word processing (1 mk)

b) List
down examples of word processing packages in the market today. (2mks)

15 a) what are the characteristics of (ROM) (2mks)

b) The diagram below is of a common port in a computer system

i. What is the name of the port shown above (1 mk)

ii. What are some of the examples of devices that can be connected to the above port?

(2mks)

SECTION B

Answer question 16 and any other three questions from this section in the Answer

sheet provided.

16 a) Define the terminologies;-

i) Source code

ii) Object code (4mks)

b) With an aid of a pseudocode and flow chart, write a computer program that can be used to compare the values of two numbers and print the largest number. (11 mks)

17 a) State any three reasons why people may resist the introduction of computers at their place of work (3mks)

b) Outline other threats facing computers in this modern world. (3mks)

c) State four factors to consider when purchasing a memory for your computer.

(4mks)

d) State three salient features of a computer output (3mks)

e) State the function of the following MSDOS commands

i) REN (1mk)

ii) DIR/P (1mk)

18) a) Distinguish between the following sets of terminologies used in spreadsheets

i) Work sheet and work book . (2mks)

ii) Filtering and sorting (2mks)

b) State one way in which a user may reverse the last action taken in a spreadsheet

package. (1mk)

c) The following is the sample of a payroll. The worksheet row and column heading are

marked 1,2,3…. and A. B, C…. respectively

Use the following expressions to answer the questions that follow

• BASIC PAY = hrs marked X pay per hr

• ALLOWANCES are allocated at 10% basic pay

• CROSS PAY basic pay + allowance

• TAX deducted are calculated at 20% gross pay

• NET
PAY gross pay-tax deducted

Write a formulae using cell reference for the following:

1) D2

2) E4

3) FI0

4) G7

5) H5 (5mks)

d) i) State the ways of editing the contents of a cell in Microsoft excel. (3mks)

ii) State two of how information and communication technology (ict) can be used to reduce the spread of HIV/AIDS (2mks)

19 i) with the aid of a pseudocode and a flow chart design an algorithm that

i. Prompt the user to enter two numbers x and y

ii) Divide X and Y and display the quotient. However if the value of Y is O, the program should display an error message “Error division by zero” (l0mks)

iii) State the major components found in the system unit (CPU) (4mks)

iv) What is programming (1 mk)

20 a) With the aid of a diagram explain the following network typologies

i) Ring topology.

ii) Bus topology,

iii) Star topology (6mks)

b) Define the following terminologies in relation to networking.

i) Crosstalk

ii Noise

1. Attenuation

1. Frequency (4mks)

c) State two advantages of and two disadvantages of wireless communication (4mks)

d) List down one major advantage of networking. (1mrk)

MARKING SCHEME

SAMPLE PAPER 8

451/1

 1. i) Type of ROM once written by the manufacturer its contents cannot be deleted

ii) Type of Rom whole contents may be erased by exposing it to ultra violet light

 2. i) To co-ordinate the activities of the computer system during the execution of a program

ii) performing the operations like data transfer arithmentic calculations and decision- making.

1. State of instructions and data needed by the program currently being processed

3. a) Programming language that uses binary codes i.e. 1s and 0s

 b) A low level programming language uses binary codes as processing codes while

high level programming languages uses mormonics i.e English like statements as instructions.

 4. a) – Suitable for handicapped people.

– Fast and easy method

• – Printer port
  • USB port
  • Communication port

5. a) Character based operating system uses commands to execute instructions

while graphical user interface operating system uses icons which are clicked by the use of a mouse.

b) – Keying devices

– Voice recognition input devices

– Pointing devices

– Touch screen

 6. – Type of data to be entered into the computer

– Cost

– Speed

 7. – No smoking in the lab

– No carying of liquids and eatables

– All windows should be open to allow free air movement

 8. a) Optical bar code recognition (OBR)

 b) At point of sale terminals e.g. in super markets

c) The bars may contain specific information about the item sold e.g – type of commodity

– Cost

– Quantity

– Manufacturer etc

 9. a) A memory location

b) Help especially when one wants to use a specific memory location to store data temporily.

10.- Base band: Signals are generated and applied to the transmission medium directly without modulation.

 –Broad band : Analog signals sent over a transmission medium at a particular frequency

 11. 31₁₀ – 17₁₀

31₁₀ into Binary = 0011111 ₂

17₁₀ into Binary 0010001₂

0010001

1^s compl. 1101110

Add 1 + 1

1101111₂

Add to 31 i.e 0011111

 + 1101111

 (1)0001110

Overflow therefore ignored

Answer = 0001110₂ 14₁₀

 12. i) Algorithm is a set of rules used to solve a given task .Wrongly designed rules will

result to errors when executed.

1. Transposition errors result from incorrect arrangement of characters e.g. writting 396 instead of 369

1. It provides Internet services and Internet communication.(Internet services provider)
2. a) When text automatically re-adjust itself to the next line.

   b) – Microsoft word

    – Word pad

    – Word pro

    – Omin – pro etc

3. a) – Read only

• Non-volatile i.e. its contents do not disappear once written stores permanent data.

b) i) USB: (Universal serial bus)

 ii) Keyboard

 iii) Mouse

 iv) Printer

 v) Flash disk etc

1. a) i) Program code that the programer enters in a program editor window that is not

   yet translated into a machine readable form.

ii) Program code that is in machine readable form

1. Start :

   Print” Enter two numbers X and Y”

   Input X,Y

    If YX Then

    Print”Y”

 ESE

 Print X

 End If

Stop

Start

X , Y

No

Y  X

YES

Y = largest X = Largest

1. a) – Lack of skills

• Job displacement
• Expensive
• Environmental factors i.e Disposal
• Risky as may entertain theft
• Eye problem
• Backache

1. Constant change of technology that may require the organization to keep on training their staff.
2. – Speed

• Upgradability
• Cost
• Performance

1. – Quality

• Validity
• Usefulness

e) – REN: Renaming a file or a folder

– DIR/P: Displays directory contents per page.

1. a)i) – Worksheet : An area where you type data.

• Workbook: Combination of several worksheets.

ii) – Filtering : To get specific data in a worksheet.
– Sorting: Arranging of the records in a specific order.

1. Use the undo command.
2. i) D2: _

   = B2 X C2

   1. E4:_

   = 10 % x D4

   1. F10:_

      = D10 + E10

   2. H5 :_

      = 20% X F7

3. i) – F2 key when pressed

• Using the formular bar
• Double clicking bar containing the data and editing

ii) Through the sending of E- mails to people to warn them watching of videos(edvative ) in schools to advocate the young ones against dangers

1. START

   PRINT “Enter 2 numbers X and Y”

   INPUT X,Y
   IF Y = 0 THEN

   PRINT ” Error ! Division by zero”

   ELSE

   Quotient = X/Y

   END IF

   STOP

Start

X , Y

YES

Y =0

NO

ERROR :”DIVISION BY O”

QUOTIENT = x/y

Quotient

Stop

ii) – Mother board

• Drives
• Power supply
• Internal databases
• Main memory

1. The act of writing coded instruction to perform a task

20. i) Ring Topology

A

 B

D

HUB C

 ii) Bus Topology

 A C

B D

 iii) Star topolgy

D A

HuB

B C

 b) i) Cross
talk:

When two frequencies intercross one another

ii) Noise: Unwanted data signals in a transmission media.

iii) Alternation:

Decrease in magnitude and energy as a signal progressively moves along

a transmission media.

iv) Frequency: Number of oscillations in one seconds

• Advantages: -Does not need physical connections

  – Can reach even remote areas ie large areas

  Disadvantages
  

  • Expensive
  • Relatively difficult to establish
• Resources sharing.