A file is a collection of related data given a unique name while a folder is named storage location on a storage media that contains related files

• The OS allocates CPU time to each process, and prioritises them in the order of importance

Virus / trojan / worm / malware

• Piece of software/code/a program that replicates itself  or causes damage e.g. editing/deleting files

Prevention

• Running anti-virus/anti-malware software 
• don’t download from unknown sources
• don’t click on unknown links

Spyware / malware / keylogger

• Piece of software/code/a program that records actions/key presses and sends this data to a third party analysis

Prevention

•  Running anti-spyware/anti-malware software/firewall

Data interception / passive

• Data is sent to another device and is intercepted by a third party

Prevention

• Encryption

Phishing

• An e-mail has a link that when clicked directs the user to a fake website that collects personal data

Prevention

• Network policy // firewall

Pharming

• A piece of code installed that redirects user to fake website that collects personal data

Prevention

• Anti-malware or firewall

Hacker

• Person attempting to gain unauthorised access to the network/computers/ data/files 
• unauthorised access and then deleting/editing data/files

Prevention

• Firewall
• strong password 
• biometrics
• penetration testing

17. a) i) Explain the term search as used in the Internet.                                            [2]

A web based application that locates items or information from the World Wide Web

ii) Peter intends to download a movie from the Internet. State the three factors that may determine the total time taken to complete the download.                                           [3]

• Size of the video/format
• The bandwidth of the media/speed of network/network traffic
• Type of browser software
• Background activities running in the computer
• Restrictions enforced in the computer/firewall/antivirus
• Speed of the computer/CPU speed
• Size of RAM

b) Wakulima online is an organization that runs a web based system for assisting farmers to obtain market for their produce. State four technological reasons that may cause a farmer not to access the organization’s system.                                                                                  [4]

• Poor network/lack of connection
• Software failure in the system

• Hardware failure
• Lack of access rights
• System overload/hanging
• Lack of skills/disability/illiteracy
• Lack of power supply

c) Explain a situation when each of the following Desktop Publishing program features may be used when creating a publication:

i. Cropping                                                                                                               [2]

Applies to graphics – used to trim/remove/hide some portions in the graphics

ii. Transparency                                                                                                         [2]

Used to make background of a graphic to be clear/visible

d. List two areas where infrared waves are used in data communication.                             [2]

18. a) List four activities of the planning stage of systems development.                             Ignore this question, marks redistributed elsewhere

b) Explain a circumstance when each of the following feasibility studies are carried out during systems development.

i. Technical                                                                                                               [3]

Done to determine whether technology exists to support the proposed solution

ii. Economic                                                                                                              [3]

Done to determine whether the proposed solution is economically viable

iii. Schedule                                                                                                               [3]

Done to determine whether the proposed system can be done within an acceptable time.

c) Table 1 and Table 2 are related tables in a database. Use them to answer the questions that follow.

Table 1

Table 2

i. Identify the appropriate primary key for each table.                    [2]

Table 1 – Dept code, Student Registration No

ii. Explain two benefits of enforcing referential integrity in the database. [4]

• No record can be added in Table 2 if its corresponding record in Table 1 does not exist
• No record in Table 1 can be deleted without first deleting the corresponding record in Table 2
• Reduces data redundancies/ensures integrity
• Prevents deletion of related table

19. a) Describe each of the following validation checks as used in data processing.

i. Preserve check                                                                                                      [2]

Ignore this question, marks redistributed elsewhere

ii. Data type check                                                                                                    [2]

Ensure correct type of data is entered for the field

iii. Check digit                                                                                                           [2]

This is a number added/calculated by the computer to a binary number. The check digit ensures correct transmission of the binary number.

b. Write each of the following abbreviations in full:

i) BCD                                                                                                                                    [1½]

Binary Coded Decimal

ii) EBCD                                                                                                                                 [

This question was thrown out and marks redistributed elsewhere

iii) ASCII                                                                                                                    [1½]

American Standard Code for Information Interchange

c) Using 10-bits binary number system, perform the following decimal operation using two’s complement.                                                                                                                                   [6]

12910 - 12810

+129 = 00 1000 0001

128 = 00 1000 0000

-128 = 11 0111 1111 (ones complement)

                            +1

          11 1000 0000 (Twos complement)

129- 128

     00 1000 0001

+ 11 1000 0000

 100 0000 0001

Hence = 00 0000 00012 or 12 (the overflow bit is ignored)

Program counter // PC
• Stores the address of the next instruction to be fetched
Memory address register // MAR
• Stores the address where data/instruction is to be read from or saved to
Memory data register // MDR
• Stores data that is about to be written to memory // Stores data that has just been read from memory
Current instruction register // CIR
• Stores the instruction that is currently being decoded/executed

Ochieng manages a network for an organisation.
(a) Two computers are assigned the same IP address.
Explain why Ochieng must change the IP address of one of the computers.

• Devices must have a unique IP address because otherwise, a switch would not know which of the two was the correct device to send packets to

(b) Identify the network topology that requires a server.

• Star topology

IMAP

• Retrieves/accesses/downloads (a copy of an) e-mail
• Allows synchronisation/management of account

SMTP:

• Sends/forwards/transmits e-mai

• Is the protection of programs and data in computers and communications systems against unauthorized modification, access or disclosure
•  

• to enable logon information to be kept on his computer
• to provide pages customised for Ahmed the next time he logs on
• to implement shopping carts and one-click purchasing
• to be able to distinguish between new and repeat visitors to the website

• online storage
• incremental backup
• full backup
• RAID (level 0, 1, 10)
• uninterruptible power supply (UPS)

• Because it will be subject to movement  and it does not use mechanical/moving parts

          OR

• Solid state storage is smaller/more compact so better suited for a wearable device

          OR

• Doesn’t have moving parts  because they could be disrupted during use

Advantages

• It is quicker to type commands
• Little memory needed
• Little processing power needed

Disadvantages

• Commands have to be typed precisely
• There is a large number of commands to be learnt
• It is not user friendly
• The user has to remember commands
• Users cannot transfer data between applications

• An end user license agreement (EULA) describes a contract (agreement) between a software developer and a user of that software.
   

• Broadcast Radio
• Infrared
• Bluetooth
• Microwaves
• Satellite

SECTION A (40 MARKS)

ANSWER ALL THE QUESTIONS IN THIS SECTION

1.Compare the two types of diskettes used in microcomputers in terms of physical size and densities.    (2mks)

2.Why is it necessary to have a UPS in a computer laboratory?  (2mks)

3 a) Explain what is meant by batch processing   (1mk)

   b) Give one advantage and one disadvantage of batch processing ( 2mks)

4. List any four high level programming languages  (2mks)

5.A 3 by 4 matrix M is to be added to another 3 by 4 matrix array N so as to give a third 3 by 4 matrix array P.  Using a high level programming language, write a program segment that assigns the sum of M and N to P.(4mks)

6. The first column in the table below contains the formulae as stored into the cell F10 of a spreadsheet.  Enter the formulae, as they would appear when copied to the cell M20 of the same spreadsheet.  (3mks)

7.  Give three advantages of separating data from the applications that use the data in database design. (3mks)

8.  Explain the impact of information on organizations in each of the following areas:  (2mks)

   a) Competition

   b) Pace of growth

9. a) List any four tasks that an electronic spreadsheet should be able to perform other than calculations  (2mks)

    b) Explain what is meant by automatic recalculation as used in a spreadsheet.(1 mk)

10. Describe the functions of the following computer hardware components:

   a)Mouse                     (2 ½  mks)

   b)Scanner.                   (1 ½ mks)

11. a)State two differences between Disk Operating System (DOS) and WINDOWS operating system.

 b. i) Define the term application software  (1mk)

     ii) Give one example of application software (1mk)

12. a)  Give one difference between internal and external commands in Disk Operating System.   (2mks)

      b)  Name two DOS commands that may be used for checking disk errors.  (2mks)

13. Explain how a paragraph can be moved from one place to another in word-processing. 2mks)

14.  Define the term structured programming. (2mks)

SECTION B (60MKS)

Answer question 15 and any other three questions from this section.

15.a)  What is meant by each of the following terms:

 i)   pseudocode        (1 ½ mks)

  ii)  Flowchart           (1 ½ mks)

b) a program is required to list the first 1000 numbers in the series:  2, 4, 6, 8,

10. Draw a flowchart and write a program that can be carried out this task.   (12 mks)

16. The following car details are to be entered in a database; make, date-of-manufacture, colour and cost.

 a) Prepare a suitable database structure showing field names and their field types   (5mks)

 b) Explain how you index the data such that cars of the same make and colours are together   (2mks)

 c)  Write a statement that can be used to select cars of the colour green        (2 mks)

 d) Give an instruction that would;

  i)select cars whose cost lie between 500,000/= and 1,000,000/=  (3 mks)

 ii)Determine the average cost of all cars         (3mks)

17.  a)The diagram below represents the essential features o a computer system. Study the diagram and answer the questions that follow:

i)Name the components (4mks)

            A

            B

            C

            D

ii) On the diagram above, indicate the direction of data flow using arrows.  (3mks)

b) Name the three types of buses in a computer system (3mks)

c) Explain how CPU registers may be used to carry out a basic calculation such as:2 + 7 = 9

d) Name two computers output devices. (1 Mark)

18. a)State three ways in which computer technology may affect employment patterns in organizations   (3mks)

b) State three ways in which computer technology may affect employment patterns in organizations (3mks)

c)Suggest three strategies that can be employed to manage resistance to change  (3mks)

d) Give three advantages of computerization in an organization.  (3mks)

19. a)In a computer based information system, state the purpose of the following files and give one example where such a file may be required in a school.                (8mks)

i) report file

ii)Back-up file

iii)Reference file

iv) Sort file

b) State three precautions that should be taken to ensure that diskettes are well stored.  (3 mks)

c)  Distinguish between “serial” and Indexed sequential” file organization methods.  (2mks)

d)  Distinguish between binary and octal number systems and give an example of each  (2mks)

Branch of computer science based on enabling computers to
behave like humans/mimic aspects of human intelligence
• AI is implemented in software.
• Combines psychology, biology, linguistics, mathematics, neuroscience,
and philosophy (ethics)
• AI is not the same as the general intelligence of human beings

Uses – Any of the following:
• Game playing (chess, quiz, video games)
• Analytics (analyse buying patterns, predicting behaviours, predictive
text, financial markets)
• Image processing (recognising objects/patterns)
• Logistics (scheduling, order fulfilment)
• Control systems (cars, manufacturing, weapons, navigation)
• Expert systems (medical, mechanical, electrical diagnosis)
• Neural networks (simulating neuron behaviours as in brains)
• Natural languages processing (chatterbots, chatbots, speech
recognition)
• Robotics (dangerous situations, help aged or disabled)

Ethical issues – Any of the following:
• Take the work of humans, thereby affecting employment rates
• Is a computer to be trusted to make decisions (life-death)?

• If a computer discovers something that humans can’t prove, should it be
accepted as truth?
• Do AI machines have rights?
• Will people be comfortable interacting with machines that are
considered intelligent?

DVD - optical media which use one spiral track; red lasers are used to read and write data on the media surface; makes use of dual-layering technology to increase the storage capacity

ROM - non-volatile memory chip; contents of the chip cannot be altered; it is often used to store the start-up routines in a computer (e.g. the BIOS)

SSD/ Solid State Drive/memory (SSD)

non-volatile memory device that uses NAND flash memories (which consist of millions of transistors wired in series on single circuit boards)

Blue Ray -  optical media that uses blue laser technology to read and write data on the media surface; it uses a single 1.1 mm polycarbonate disc

• Knowledge base – is the systems’ database of knowledge about a particular subject. It contains relevant facts, beliefs, assumptions and procedures for solving a particular problem
• Inference engine – this is the software that controls the search for knowledge in the knowledge base and produces conclusions. It takes the problem posed by the user and seeks to analyze it in order to arrive at a conclusion.
• User interface- this is the display screen that enables the user interact with the system.

• loss of jobs as some traditional shops/banks close
• lower profits for companies that do not get involved with e-commerce
• decline of leisure shopping as goods are bought on-line
• city centres becoming deserted as shops/banks close down
• gap between rich and poor widening as richer get savings from
• shopping on-line
• more people choosing to interact with computers rather than people
• increase in small businesses
• less pollution/travelling