Data and instructions are fetched from main memory, from addresses requested by the CPU on the address bus. (Data and instructions are sent) using the data bus. (Data and instructions are then) decoded and executed in the CPU.
Results of operations are sent back to the memory on the data bus

CLI

• Commands have to be typed in full with no mistakes
• Requires memorization of commands
• Uses less memory

GUI

• Due to graphics, GUI uses a lot of memory
• GUI is more user friendly
• Cannot operate properly if memory is low

Comparison

• Both carry out file management
• Both are operating systems
• Both control software and hardware

b) Study the following pseudocode and answer the questions that follow.

1. Start

2. Get Value1 and Value2

3. If Value1> Value2 Then

4. Maximum = Value1

5. Else If Value1< Value2 Then

6. Maximum = Value2

7. Else Go to 9

8. Display Maximum

9. Stop

i) State the purpose of the pseudocode                                                                                  [1]

To compare two values and output the greater of the two

ii) Draw a flowchart equivalent to the pseudocode.                                                                     [8]

• reduced labour costs/do not need paying
• reduced cost of goods
• improve speed of production/productivity
• high degree of accuracy/precision/less errors
• can operate where humans can not go
• do not take breaks/holidays/get tired
• work 24 hrs a day
• reduce accidents at traffic lights
• improve traffic flow
• can work in dangerous conditions

• novice can use the system right away
• user-friendly/easy to select
• click on icons/picture to select
• easier to input/words are replaced with icons
• no need to know command language to use the system/remember
• command language
• selecting item using mouse is faster than entering commands
• avoids typing errors
• no need to type
• no need to remember commands
• no need know the different commands for the different software
• multitasking (several programs open at the same time therefore easier
• /faster to switch
• easier/faster switching between files, folders etc.

• Authenticity
• Users' needs
• Availability of documentation
• Cost
• Compatibility
• Upgradability
• Portability

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

• compact disks
• DVDs
• Blue Ray

• It is an address to a resource on the internet

• Allows creation and management of user accounts
• Helps in troubleshooting of the network
• controls access to network resources
• Provides communication services
• configures network resources
•  

• two's complement has only one value for zero

Multi-tasking - It is a data processing modes where a single CPU processing more than one task or program apparently at the same time

Time-sharing - a processing mode where a single CPU processes tasks from more than one user apparently at the same time

Time-sharing - this is a processing mode in which the CPU serves two or more users with different processing requirements ( tasks)

On-line processing - is a mode of processing where the result of data processing transaction is available immediately

Real-time processing - is a mode of data processing in which the time interval required to process and respond to inputs is so small that the response itself is useful for controlling the physical activity of a process

• Patient monitoring
• Used to control medical equipment e.g ultra sound
• medical research and studies
• communication and telemedicine

– when transferring large files/attachments with emails
– when streaming music/video files/bit streaming
– when using VoIP/video conferencing
– software updates
– online transactions
– Using VLE (Virtual Learning Environment)

(a) Disk mirroring- Data is written on two or more disks simultaneously.

(b) Encryption - Contents are scrambled so they cannot be understood without a decryption key

(c) Backup - A copy of the data is taken and stored in another location

• a computer that responds to requests to provide information and services over the Internet - an Internet server
• defines how messages are transmitted and formatted over the Internet-HTTP
• software that enables users to access/view documents and other resources on the Internet - Browser     
• numerical ID for each device on the Internet-IP address
• unique ID for a network interface card  -MAC address

A computer virus is a program designed to damage other programs or causes irregular behaviour in a computer system.

Explain the purpose of each of the following features of a spreadsheet chart (KCSE 2021, Q19 (a))

Legend

• Legends are a small visual representation of the chart's data series to understand each without confusion.

A data series

• is a row or column of numbers that are entered in a worksheet and plotted in your chart, such as a list of quarterly business profits
• A group of related data points or markers that are plotted in charts and graphs

Data Marker

• A symbol on the chart that represents a single value in the worksheet.
• A column, dot, pie slice, or another symbol in the chart representing a data value

https://www.lifewire.com/data-series-data-points-data-labels-3123411

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

• Ease of installation and use
• Application software intended for use in the computer
• Processor type. Some processors do not support all operating systems