KCSE Past Papers 2019 Computer Studies Paper 1 (451/1)

2019 Computer Studies – Paper 1

Section A

Answer all the questions in this section

1. State the hardware technological differences between the second generation and the third generation computers (2 marks)

The 2nd generation use transistor in its logic circuit while the 3rd generation used integrated circuit.

2. State two ways of ensuring proper ventilation in a computer room. (2 marks)


  • Having large windows
  • Having windows and vent area opened Using air conditioning equipment
  • Providing spacious seating arrangement3. Convert the decimal number 20.373 to its binary number system equivalent. (2 marks)

    20 = 101002

    .375 x 2 — 0.750

    .750 x 2 = 1.500

    .500 x 2 = 1.000

    The integer digits read down = 011

    20.37510 = 10100.011

    4. Peter has installed internet in his home computer in order to use it for browsing. State three ways in which he would prevent viruses from infecting his computer. (3 marks)


  • Using antivirus shielding software
  • By surfing smart, i.e. those site which are credible
  • Using a firewall to deter unwanted packets from accessing the computer from the internet
  • Install anti
  • spyware to prevent real time spying of the computer
  • Not using storage media which has been used in suspicious computer
  • Using complex and secured password to restrict access
  • Enabling security settings of the browser5. State three ways of transforming a picture embedded in a Desktop Publishing programme in order to fit in a designated space on a document. (3 marks)


  • Rotation
  • Flipping
  • Cropping
  • Stretching6. Differentiate between a line printer and n page printer as used in computers.(2 marks)

    A line printer is an impact printer that prints one entire line of text at a time while a page printer is a non impact printer that prints a whole page at a time.

    <b<7. describe=”” virtual=”” reality=”” as=”” used=”” in=”” computers.=”” (2=”” marks)=”” <=”” b=””></b<7.>

    Virtual Reality is the computer generated simulation of a three-dimensional image or environment that can be interacted with in a seemingly real or physical way by a person using a specialized electronic head gear.

    8. State the function of each of the following features of an email software:

    (a) Inbox (1 marks)

    A storage location where new email messages are stored .

    (b) Draft (3 marks)

    A storage location where messages composed but not yet sent are stored

    9. (a) Explain the term toggle key as used in computer keyboard. (2 marks)

    These are keys that alternate the input mode. When pressed ON they are intended to perform a task, when OFF, they perform different task.

    (b) List examples of toggle keys on a computer keyboard. (2 marks)

    Caps lock, Insert, Num Lock and Scroll lock

    10. State the type of error that would occur in data processing for each of the fol1owing cases:

    (a) Entering the number 315 instead of 351. (3 marks)

    Transposition error

    (b) Entering the text “Kwys” instead of “Keys”. (3 marks)

    Transcription error

    11. State four factors to consider when selecting an input device for use in a computer room (4 marks)


  • Compatibility with the existing system
  • Cost of the device
  • The extra features in the device
  • The purpose of the device
  • The speed in which input of data is required
  • The nature of data to be captured12. State three functions 0f Un-interrupted power supply (UPS). (3 marks)


  • Protects devices against high or too low voltage.
  • Provides temporary power supply in case of sudden power outage
  • Processing wave form distortion.
  • Stabilizing the frequency
  • Surge protection.
  • Suppress transverse mode noise.13. Distinguish between a page break and a column break as used in a word processor. (3 marks)


  • Page break is a code inserted by a WP program that instructs the printing device where to end the current page and begin the next.
  • Column break is a feature that breaks a column and starts the next column.l4. State three factors to consider when selecting an operating system to install in a computer (3 marks)


  • The hardware configuration of a computer
  • The type of computer in terms of size and make
  • User friendliness of the operating
  • Number of users it can support
  • Number of processors and hardware it can support
  • Reliability and security provided by the OS.15. Differentiate between analogue data and digital data as used in computers. (2 marks)


  • Analogue data uses values that change continuously between to instances while Digital data are values that change from one value to the next in a step by step sequence.Section B

    Answer question 16 and any other 3 questions from this section.

    16. (a) Explain the term dry running as used in program development.(2 marks)

    Dry running is the process where a programmer manually works through a code to trace the values of variables and identify any error.

    (b) Explain three properties of an algorithm. (6 marks)


  • Finiteness: An algorithm must always terminate after a finite number of times steps.
  • Definiteness: Each step must be precisely be defines using an action to be performed at each step of the algorithm.
  • Input: Any operation performed needs beginning value associated with different activities in the operation.Output: An algorithm must have a form of output/results/expected value/ qualities.

    (c) To qualify to get a driving license,an applicant must be 18 years or over.

    Ten candidates applied for a driving license test.

    Draw a flow chart that would read the name and age of an applicant and display the names of those who qualify, (7 marks)

  • 17.(a) State four outcomes that may result from using incorrect requirement specifications during system development (4 marks) 
  • The system may be costing more than what was projected
  • The system will be delivered later than schedule
  • The system will not meet the user’s expectation
  • The cost of maintaining and enhancing the system may be excessively high.
  • The system may be unreliable and prone to errors and downtime.
  • The system will not meet legal requirements.(b) A school opted to use direct change over approach when installing a new system. Explain three challenges that die school may face as a result of this approach. (6 marks)


  • If something went wrong in the new system, there will be no fall back has the business has to stall till the problem is sorted.
  • There will be a period of time where no system is available because the old one is switched off and the new one is being switched on.
  • There will be a period of upheaval while the system is brand new and the school staff are finding their way around it.
  • There is a possibility of sabotage by staff since there is no time to monitor and manage resistance to the new system.(c) State three reasons that may lead an organisation to install an intranet.(3 marks)


  • Used to isolate the organizational resources from the internet/security.
  • Used to provide communication and collaboration among individual within the organization/remote control.
  • Used to publish and share valuable information among the users easily, inexpensively and effectively via portals and intranet website/resource sharing.
  • Used to run critical applications that support business decision making.
  • Distributed processing facilities.
  • Cost Effectiveness.
  • Protects signal distortion.
  • Protects signal interference.(d) The figure below shows a coaxial cable .State the function of the part labelled A. (2 marks)


  • 18. (a) State three hardware devices that may be required to connect a computer to an existing local area network. (3 marks) 
  • A network adapter/network interface card
  • Network medium/cable
  • RJ45 connectors/BNC/ST connector/SC connectors/Fibre local connector
  • Data points (sockets to plug in the cable)
  • Switch/Hub
  • Access point/TP link(b) A publisher intends to use a desktop publishing programme to create a publication which is to have many graphics.

    State three ways in which the graphics may be acquired for this purpose. (3 marks)


  • Using digital camera
  • Scanning the graphics from other sources
  • Downloading from the internet
  • Drawing from scratch/Drawing tools
  • Clip art
  • Another file(c) Interpret each of the following spread sheet formula :

    (i) =countif(D2:D9,”>”$B4) (2 marks)

    Count those value in the range D2 :D9 with values greater than the value in cell B4).

    (ii) =sumif(B3:B11,”4M”,D3:D11)

    Sum the values in the cell range D3 : Dll for records whose corresponding values in cell range B3 : B11 equals to “4M”

    (d) (i) The following are Ellie fields of products fable in a database created to store records of products manufactured in a factory:

    • product number

    • product name

    • price

    • product description

    i. State the appropriate data type for each field. (2 marks)


  • Product Number — Number/Auto number/Text Product Name — Text/string
  • Price — Currency/Number
  • Product Description — Memo/Text/StringII. State three properties to be put in place during table design to ensure integrity of the data entered. (3 marks)


  • Data type
  • Validation/Validation rule
  • Input mask
  • Setting required/null value status
  • Field size
  • Caption19. Explain three features of a graphical user interface as used in computers (6 marks)


  • Windows — a rectangular area on the screen where the commonly use application run.
  • Icons — A picture or symbol which is used to represent a software application or hardware device.
  • Menus —a list of options from which the user can choose what that they require.
  • Pointer – a symbol such as arrow which moves around the screen as the user move the mouse.(b) State the function of each of the following computer keyboard keys:

    (i) Caps Lock (1 marks)


  • It’s a toggle key when ON, the characters typed are in uppercase when OFF, the characters typed are in lower case.(ii) Shift (1 marks)


  • Used to enable uppercase letter to be printed when alphanumeric keys are pressed. @l
  • Used with other keys to modify behavior/function key.(iii) Home (1 marks)


  • Used to take the cursor to the beginning of the line in a word processor. @l
  • Evidence of movement of the cursor.(c) Using two’s complement notation,determine the value of the operation 2510-2910

    (6 marks)

    25 — 00011001

    29= 00011101

    2’s Comp(29) = 1110 0010 + l = 1110 0011

    Adding the two binary numbers 0001 1001

    1110 0011/ 1111 1100

    No carry bit hence 2’s complement of the sum is obtained and the resulting is negative

    2’s Comp(1111 1100) = 0000 0011 +1 = 1002

    = -410 “

    20. (a) Distinguish between computer Aided Instruction (CAI) and computer Aided Learning (4 marks)


  • Computer aided instruction is an interactive instructional technique/ drill and_practice.where by a computer is used to-present-the instructional material and monitor the learning that takes place.
  • Computer aided learning is the use of computers to aid in the education or training. (b) (i) State four activities that may be carried out when disposing off an old system in an organisation. (4 marks) 
  • Confidential information must be removed/Backup.
  • All accounts or access control facilities associated with the equipment must be destroyed.
  • Installation of the new system.
  • All potential clues such as configuration settings must be destroyed Storage devices which had sensitive information should be destroyed. The equipment to be disposed in proper manner.(ii) Ways of getting user specifications during system’s design


  • Sampling of existing documents
  • Conduct research and visits the sites
  • Observation of work environment
  • Use questionnaires
  • Conduct interviews
  • Use prototyping approach
  • Use Joint Requirement Planning (JRP)
  • Automated method(c) State three benefits gained from the advancement in technology in the music industry (3 marks)


  • Few raw materials are used in the production of the media
  • No more need for big warehouses to store music materials
  • Delivery companies has less volume of deliveries
  • The use of online material is environmental friendly.
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