• Extra bit on each data-byte that
•  Does not transmit data
• Makes the number of ones in a byte always even or always odd
• Error in the transmission of a bit will make the even/odd wrong
• The problem of two errors in one byte not being found
• Parity block

(a)Explain why programmers prefer to represent instruction in hexadecimal rather than in binary

• A larger number of values can be represented using fewer characters.
• the shorter length and more characters make the pattern easier to read and understand
• recognisable character codes can be used for debugging

(b) Give two other uses of hexadecimal

• HMTL color codes representing RGB spectrum in the web development
• representation of MAC and IP addresses allowing a larger combination of unique addresses

• Registers are small amounts of memory available that hold data fetched from memory or data waiting to be stored in memory. A temporary holding place for the instruction that has been fetched.
• The system clock purpose is to determine the pace of the cycle, each tick of the clock a part of the fetch-execute cycle occurs. Regulates the timing and speed of a computers systems functions.

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)

• it is a format style that shows the listed items of different levels rather than at one level. Each level has a different indentation and numbering style

1. Chapter 1

     1.1. Introduction

                 1.1.1.Definition of terms

Any four of:
Sequential:
• Individual instructions are executed one after another
• Flow control is accomplished by jump/branch/goto instructions
• Results are usually achieved less quickly than parallel processing (do
not award twice)
Parallel:
• Individual instructions can be routed to different processors for
simultaneous execution
• Results are usually achieved quicker than sequential instruction (do not
award twice)
• Requires multi-core processors or multiple microprocessors
• Tasks may be split into different parts with each part executed on a
different processor
• Results need to be merged back together after completion

State the function of each of the following keys on the computer keyboard :  (2mks)

Backspace;

• Deletes characters to the left of the cursor

Insert

• Add characters at the cursor position
• Toggles between overtype and insert modes

An organization intends to replace an existing system by carrying out the process in stages .

Name the implementation strategy ;  (1mk)

• Phased change-over

Give two reasons why the  organization is opting to use the implementation strategy  in (a) above     (2mks)

• Gives employees time to learn
• Organizations can revert to the old system in case of failure
• Reduces resistance by the employees
• It is easier to find system errors as you are dealing with only one part at a time
• Accessing parts of the old system is still is possible in case of failure of the new system

A manager wishes to replace the current manual system with a computerized one. Describe three areas that must be evaluated to justify the replacement  (6 marks)

• Technical feasibility

• Does the current technology suffice

• Economic feasibility

• Benefits outweigh costs/ whether the project is cost effective

• Schedule feasibility

• Can it be done within the schedule

Headache, back and neck pain may result from the use of computers. State how each of them can be minimized                               (2mks)

• Proper lighting
• Regular breaks
• Use of antiglare
• Correct position of the screen
• Ergonomic furniture

Students of a school intended to elect their school Captain by secret ballot.  State three ways in which computers can be used to improve the election process                          (3mks)

• Registrations of voters
• Voter identification
• Actual voting
• Tallying

Explain why intranet is a more secure way to share files within an organization compared to internet (2mks)

• Intranet involves the interconnection of computers  within  the organization hence it is easier to monitor the access and sharing of files since the users in an organization can be assigned accounts and passwords which will enable to access files they are authorized to access unlike the internet where many can access what is stored in the organization’s website

List two career opportunities directly associated with computer networking               (2mks)

• Network administrators
• Network engineers
• Network technicians

Distinguish between a formula and a function as used in spreadsheets

• A formula is a mathematical expression that returns a value
• A function is an excel inbuilt formula that returns a value given a range of values or arguments

 The C directory of a computer has folders named Form 1, Form 2, Form 3 and Form 4. Each class has students’ folder named according to their admission number.  The student created their own folder for subjects they are studying based on the table below:

Domain integrity - ensures that all data in  a field contain valid values

1. SECTION A
2.  Answer all questions in this section
3. What is a computer?                                                                                                            1mks
4. State three physical components that make up a computer                                                 3mks
5. State the hardware technological differences between the second generation and third generation computers                                                                                                          2mks
6. State and explain three characteristics of a computer                                                         3mks
7. State the functions of the following special memories in a computer                                3mks
8. Buffers
9.  
10. Registers
11. Cache
12.  
13. Define the following as used in data representation in a computer                                  (5mks)
14. Bit
15.  
16.  
17. Byte
18.  
19.  
20. Nibble
21.  
22.  
23.  
24. Word
25.  
26.  
27.  
28. Word-length
29.  
30.  
31. State two reasons why a DVD is superior to a typical compact disk                               (2mks)
32. State three advantages of flat panel monitors over cathode ray tube monitors                   3mks
33. Explain the following terms as used in word processing                                                  3mks
34. Section breaks
35. Thesaurus
36. Superscript
37. State two advantages of  impact printers                                                                             2mks
38. State the function of the following keys on the computer keyboard                                  3mks
39. Enter key
40. Insert key
41. Delete key
42. State the technology used by the following secondary devices to store data                      3mks
43. Magnetic storage devices
44. Solid state storage devices
45. Optical storage devices
46. State three reasons why an operating system is important in a computer                         3mks
47. A typical computer’s main memory consists of both volatile and non-volatile memory.
48. i)  Explain what is meant by the term volatile memory                                          (1mark)
49. ii) What is normally stored in the non-volatile part of a computer’s main memory (1mark)
50. Explain why having cache memory can improve the performance of the CPU         (2mks)
51. What is a computer system?                                                                                           (1mk
52. Give two differences between a solid state drive (SSD) and a hard disk drive (HDD)   2mks
53. State three categories of software classified according User license agreement              (3mks)
54. State two disadvantages of Random Access Memory                                                       (1mk)
55.  
56.  
57. a) Explain the functions performed by the following components of a processor   (2 marks)
58. Control unit

• RSI in wrists or fingers from prolonged typing or repeated clicking of mouse button
• headaches/eyestrain/dry eye from staring at a monitor for long periods of time/glare from monitor
• back ache/strain from sitting in the  same position for a long time/using chair with no adjustment

• A physical file contains the original data whereas a logical file does not contain any data
• A physical file contains one record format while a logical file can contain up to 32 record formats
• A physical file can exist without a logical file while a logical file cannot exist without a physical file

• deskilling – software has removed the need for some of the more traditional skills e.g. using CAD
• (re-)training – work practices have changed; need to learn how to use the new software/computer
• redundancy – new technology allows work to be completed by fewer staff/out-sourced to “cheaper” work forces in foreign countries
• work from home (etc.) – use of emails, VoIP, video conferencing, instant messaging, etc. allows working away from the office
• – nicer/safer workplace – quieter (no noisy typewriters) and safer (no heavy filing cabinets)
• – health (& safety) – RSI, headaches, backaches