Manages memory (RAM) 

• Allocates memory to programs currently executing •

Ensures programs/data do not corrupt each other: Ensures all programs and data including itself is stored in correct memory locations

Manages processes: Ensures different processes can utilise the CPU and do not interfere with each other or crash •

Allows a user to run programs : On a multi-tasking O/S ensure that all tasks appear to run simultaneously

• Allocates time slices 
• Scheduling of programs
• Handles interrupt
• Allows a user to configure hardware

System analyst

Web designers

Network administrators

Database administrators

Programmers

Computer technicians

MAR( memory address register)

• Stores the address/location where data will be read/written/accessed/fetched
• stores address/location of data/instruction being processed
• stores address/location of data/instruction next to be processed

MDR or  memory data register

• Stores the data/instruction that is fetched/read from memory
• stores the data that is to be written to memory
• stores the data/instruction from the address in the MAR
• stores data/instruction next to be processed

 Program counter

• Stores the address/location of the next instruction to be run
• stores the address/location of the current instruction being run

Accumulator

• Stores the result of manipulation/process/calculation

– faster communications now widely available
– safety reasons, e.g. increase in terrorist attacks on international flights
– reduced transportation/accommodation/hardware costs
– environmental issues, e.g. reduced carbon footprint
– increase in multinational working

• allowing the network to share resources like files and software for printers and computers
• support the network's implementation of security features
• controls user accounts
• supplies network administrators with network monitoring tools.

Incremental:

• Only the changes need to be backed up
• The software/OS/settings are unlikely to have changed between backups
• Small number of files likely to be used/edited between backups
• Take less time to backup
• Each backup will take less memory space to store

Full:

• Backup all the data/files and software
• It might not take a significant time to back up entire system
• He might only have a small number of files to be backed up each time
• Safer as have more past versions to revert to
• User may have changed settings on computer
• Faster to restore the backup
• Needs to do a full before he can do an incremental

• It refers to a computer that controls other computers in a network and monitors user's access to the shared resources.

Windows for example a word processing application and a spreadsheet
 
Menus, for example, allow the user to perform operations or run applications such as right-click to create a new folder  
 
Icons for example a picture of linked computers for networking
 
Pointers(mouse or touchscreen)  for example to select items/trigger events  
 
Shortcuts for example to frequently used applications for example having a shortcut to your mail client on your desktop
 
File navigation for example when searching the hard disc for a file/folder using a browser
 
copying / deleting / moving/sorting/naming/searching of files or folders for example copying of a file from the hard drive to a USB pen drive (File handling)
 
Desktop customisation for example changing the colours and background image
 
Copy and paste for example between applications e.g. copying a graph from a spreadsheet to a word processor
 
Error messages for example provide users with error/warning/help messages for example ‘printer out of paper’ 

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)

The Fetch – Execute cycle is a sequence of actions, performed by the processor as it fetches
a program instruction from its memory, determines what the instruction wants to do and
carries out those actions. The stages of the cycle are provided below.

• Fetch the instruction – the processor fetches the instruction from a memory address stored in a program counter and transfers the instruction, via a data bus, to an instruction register. At the end of the fetch operation, the counter points to the next instruction that will be read in the next cycle.
• Decode the instruction – the processor decodes the instruction stored in the instruction register, including getting any operands required to complete the instruction.
• Execute the instruction – the decoded instruction is executed.
• Store the result – the result generated by the execute phase is stored in the main memory, and/or sent to an output device. The program counter is updated with feedback from the arithmetic logic unit (ALU), to a different address from which the next instruction will be fetched.

1.State two reasons for the increased use of laptop computers in government offices. [2]

They are small and fit in a small storage space

They are light weight hence can be carried to areas where their services are required

The monitor, system unit, keyboard units are integrated together

Easy to share

Have rechargeable battery

Have low power consumption

2.Computer network technicians prefer to use command-line based operating systems when configuring networks. State three reasons for the preference. [3]

Do not take up a lot of memory

Have direct access to most hardware devices/provide complete control during configuration

Cheaper to acquire as some are freeware/shareware

Faster to execute commands

Difficult to hack/more secure

More stable

3.State three measures that should be put in place in a computer laboratory to safeguard users’ health. [3]

• All power cables must be insulated and hidden from users
• Furniture used must be of standard
• Room should have adequate lighting
• No overcrowding
• Monitor should be fitted with anti glare
• Avoid dust
• Avoid slippery floor
• Avoid bright coloured walls
• Promote use of ergonomic devices

4.State three ways in which barcode readers may be used in schools. [3]

Take inventory of items

Transactions in the school library

Keep track of movement of goods

Track students in and out of school

Used to register roll call

5.State three advantages of flat panel monitors over cathode ray tube monitors as used in computers.                                                                                                                     [3]

• Compact and light/portable/less bulky/occupy less space
• Consume less power
• Low angle distortion
• Improved color depth
• Higher resolution
• Have less radiation
• Produce less heat

6.State three possible reasons for the extinction of daisy wheel printers in the market. [3]

• Slow
• Noisy
• Lack of graphic support
• Monochrome printer
• Supported on font type and size

7.State three ways in which an operating system secures a computer system.             [3]

• User authentication
• Secure user accounts with privileges
• Encryption of data
• Keeping log files
• Auto backup and auto recovery features
• Inbuilt antivirus

8.A law firm prefers to use hard copy output when handling documents for legal matters. State two reasons for this preference.                                                            [2]

• Can be used without electricity
• Can serve as physical evidence/exhibit
• Not easy to change content without leaving evidence
• No need of computer knowledge

9.State the function of each of the following feature in a word processor

a. Thesaurus                                                                                                                    [1]

Feature that suggests words with similar or opposite meanings to the selected word

b. Comments                                                                                                                   [1]

Feature that allows a user to attach remarks

10. With the aid of an example, explain the term multi-level list as used in word processing.                                                                                                                [3]

1. Chapter 10
   1. Summary
      1. xxxxxxxx

Formatting style that shows listed items at different level instead of using one line

11. Distinguish between real-time operating system and distributed operating system. [3]

Accept answers based on data processing concept

12. Explain the function of protect sheet feature in a spreadsheet program.                   [2]

A tool/feature that prevents unwanted changes to the spreadsheet. Requires a user to key in a password inorder to make changes

13. State four computer based careers introduced as a result of computerized data processing method at the airport.                                                                                     [2]

• System analysts
• Web designers
• Network administrators
• Network technicians
• Programmers
• Database Administrators

NB/ Accept any computer based career

14. In a spreadsheet, the formula = If(A1>10,A1*77,A1*50) is entered in a cell. Interpret the results.                                                                                                                        [3]

Checks the value in cell A1if it is more than 10, if the comparison is true then the outcome of the value in cell multiplied by 77 is displayed, else if it is false the results of the value in cell A1 multiplied by 50 are displayed.

15. State a stage in systems development cycle where each of the following activities are carried out:

a. Identifying the technologies that may be used in a proposed system.                       [1]

Accept any sub stage within system analysis e.g. requirement specification, problem definition, information gathering, etc

b. Identifying shortcomings of a system.                                                                       [1]

All stages of system development

c. Preparing the system migration plan.                                                                          [1]

Implementation stage

• Main memory is transitory/temporary/volatile, secondary storage is (semi-)permanent
• The processor can only use data/instructions that are in the main memory
• Main memory is directly accessible to the processor, secondary storage is not directly accessible to the processor 

Describe how the computer on board the aeroplane uses GPS to find its exact location

– satellites transmit signals to onboard computers
– computers receive/interpret these signals
– system depends on very accurate timing/use of atomic clocks
– each satellite transmits data indicating location and time
– computer in aeroplane calculates location based on at least three satellites
– at least 24 satellites in operation at any one time
– position accurate to within one metre
– can also calculate altitude of aeroplane
– ref to “triangulation”:

Give two benefits of using GPS in this application

– safer as the known location is exact/more accurate
– reduces the possibility of pilot error
– allows accurate estimation of arrival time
– display and guide the pilot to the nearest airport in case of emergency

• Radio waves
• Microwaves
• Infrared waves

• They run only one program/task
• OS would increase development and manufacturing cost as more storage will be needed

High level languages are used in situations when:

1. Speed of execution is not a critical factor, such as in office applications.
2. a programmer needs to use complex commands that perform complex tasks.
3. A programmer wants to make use of standardised library / sub routines.

Low level languages are used in situations when:

1. a program must execute quickly such as real time applications
2. a programmer needs to write code that interacts directly with the hardware, such as device drivers
3. a programmer needs to perform a specific command not available in a HL language.

There could be several possible causes for the issues Jane is experiencing with her computer keyboard, including:

1. Software Issues
   - Cause: Outdated or corrupt system files, drivers, or operating system.
   - Solution:
     - Ensure the operating system and drivers are up-to-date.
     - Run a system file checker to repair any corrupted system files (e.g., on Windows, run "sfc /scannow" from the Command Prompt).
     - Consider reinstalling the operating system if issues persist.

2. Hardware Issues:
   - Cause: Physical damage or malfunction in the keyboard hardware.
   - Solution:
     - Check for physical damage or debris under the keys and clean the keyboard if necessary.
     - If cleaning doesn't help, consider replacing the keyboard with a new one.

3. Resource Overload:
   - Cause: The computer may be running too many background processes or lacking sufficient hardware resources.
   - Solution:
     - Close unnecessary background applications and processes to free up system resources.
     - Consider upgrading the computer's RAM, CPU, or storage if it's outdated and unable to handle current software demands.
     - Use task manager or activity monitor to identify and terminate resource-intensive processes.

4. Malware or Viruses:
   - Cause: Malicious software can slow down a computer, cause hanging, and delay startup.
   - Solution:
     - Perform a full system scan using reputable antivirus or anti-malware software to remove any threats.
     - Ensure that the operating system's security patches are up-to-date.

5. Disk Fragmentation:
   - Cause: Fragmented files can slow down the loading of applications and overall system performance.
   - Solution:
     - Run a disk defragmentation tool (e.g., Windows' built-in tool) to optimize file storage on the hard drive.
     - Consider upgrading to a solid-state drive (SSD) for faster application loading times.

6. Insufficient Storage:
   - Cause: If the hard drive is nearly full, it can cause slow performance.
   - Solution:
     - Free up space by deleting unnecessary files and programs.
     - Consider upgrading to a larger capacity hard drive or SSD if storage space remains an issue.

7. Background Processes and Startup Items:
   - Cause: Too many unnecessary programs running in the background or starting up with the computer.
   - Solution:
     - Disable or remove unnecessary startup items and background processes to improve startup time.
     - Use the Task Manager or System Preferences (on macOS) to manage startup items.

It's important to diagnose the specific cause of the issues Jane is facing by troubleshooting each potential problem one by one. In some cases, a combination of these solutions may be necessary to fully resolve the problems with her computer keyboard.

• Repairing files
• Compression
• Defragmentation
• Back up
• Anti-virus / anti-spyware / anti-malware
• Firewall
• Managing application updates
• Format disks/drives
• System analysis tools

• Radiowaves are omnidirectional while microwaves propagate in one direction at a time(unidirectional)
• Radiowaves can be propagated over long distances through sky mode while microwaves require a relay satellite to amplify and retransmit the microwaves signals to the receiver earth station