Hard disk drive

• to hold the operating system/communication and applications software/ISP software
• for storing files/information/cookies on backing store

RAM

• for data, computer programs and operating instructions which are moved into it/downloaded for data currently in use

DVD writer

• Films/videos/pictures/music/multimedia data downloaded/purchased

Modem

• link/dial up/establish communication with the Internet
• Convert digital signals to analogue/audio tones (and vice versa) Which can travel across the telephone system

(The parent can) set criteria for the websites she is allowed to visit such as a whitelist/blacklist of websites. The firewall will examine the data/traffic incoming and outgoing from her computer. If data is sent from a website that is not allowed, it will be blocked

1. Slow Performance: If your computer suddenly becomes significantly slower than usual, taking longer to boot up, open applications, or respond to commands, it could be a sign of a virus. Viruses can consume system resources, resulting in decreased performance.

2. Frequent Crashes: If your computer frequently crashes, freezes, or experiences sudden system reboots without any apparent reason, it could be due to a virus. Some viruses can interfere with system stability, leading to unexpected crashes or instability.

3. Unusual Pop-ups or Ads: If you start noticing an excessive number of pop-ups, advertisements, or banners appearing on your computer screen, especially when you're not browsing the internet, it might be an indication of adware or malware infection.

4. Unwanted Modifications: Viruses can modify system settings or configurations without your consent. If you observe changes in your default browser homepage, new toolbars appearing, unfamiliar icons on the desktop, or altered settings, it could be a sign of a virus.

5. Unusual Network Activity: If you notice excessive network traffic, unusual data transfers, or a sudden increase in data usage without any known reason, it could be an indication of a virus or malware actively communicating with external servers.

6. Missing or Modified Files: Viruses can delete, encrypt, or modify files on your computer. If you find missing files or encounter unexpected changes in file sizes, names, or extensions, it could be a result of a virus infection.

7. Disabled Security Software: Some viruses attempt to disable or circumvent antivirus or security software to avoid detection. If you notice that your antivirus program or firewall is deactivated, modified, or unable to update, it could be due to a virus compromising your security software.

8. Unexpected Email or Message Activity: Viruses can use infected computers to send spam emails or messages to contacts in your address book without your knowledge. If your friends or colleagues report receiving suspicious or unexpected emails or messages from you, it could be a sign of a virus.

• This approach causes minimum disruption

SECTION A (40 MARKS)

1.Describe the purpose of each of the following computer functional units:    (2mks)

    a) Control

    b) Storage

2.Explain how each of the following would affect the suitability of a room for use as a computer room: (2mks)

a) Burglar proofed door

b)Availability of taps and sinks in the room

3.State three data representation codes used in computers       (3mks)

4.State two types of documentation in program development and give the purpose of each.     (4mks)

5.Suppose a 5 element array A contains the values 9, 12, 17, 7 and 20.  Find the value in A after executing the loop below:

            Repeat for k = 1 to 4

            Set A [k +1]: = A [k]

                        [End of loop]            (3mks)

6.State any three activities that occur in a program compilation process  (3mks)

7.The formula = k20 + P$ 18 was typed in cell L21 and then copied to cell M24 of a spreadsheet. Write the formula as it appears in cell M24.(2mks)

8.State two ways in which a computer may be used in the efficient running of a hospital (2mks)

9.List three disadvantages of using the traditional file management method          (3mks)

10.Give one disadvantage of a single processor multi-user system    (1mk)

11. List three differences between a micro-computer and a super-computer.         (3mks)

12.State and explain two reasons why word processing is one of the most common applications of many computer users.   (2mks)

13. write- 1 in twos complement notation in byte form                                        (4mks)

14.Explain the following input/output terms as used in computer systems. Give an example for each        (4mks)

  a) Read

  b) Write

15.State two disadvantages of networking.

SECTION B (60 MKS)

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

16.The following flowchart can be used to list the odd numbers between 0 and 100

a)Write a program segment for the flowchart using a high level language.  (7mks)

b)What would be the output from the flowchart if the statement in the decision box is changed to:  (3 mks)

i)          Odd = 100

ii)         Odd< 100

iii)        Odd> 100

c)  Modify the flowchart so that it prints only the sum of the odd number between 0 and 100  (5mks)

17.a)  List five precautions that can be taken to protect data stored in diskettes   (5mks)

b)State and explain two precautions that can be taken to help recover data lost through accidental erasure. (4mks)

   c) Describe each of the following data processing methods:    (6mks)

   i) Batch processing

   ii) Distributed processing

   iii) Multiprogramming

18. a)  i)  What is a computer keyboard?      (1 mk)

           ii)  ist four types of keys found on a computer keyboard.  Give an example of each(4mks)

     b) Give four differences between present day’s computers and the older generation of computers   (4mks)

     c)   i) State three advantages and one disadvantage of using a laser printer.  (4mks)

           ii) Distinguish between a line printer and a page printer             (2mks)

19  a) Identity three public Universities and three National Polytechnics in Kenya where further computer training is offered. In case, state the highest level of qualification that can be acquired in computer training. (6 mks)

b) Distinguish between “Job replacement” and “Job displacement” in reference to computerization.  (2mks)

c) Give four reasons why a firm may decide to computerize its operations.   (4mks)

d) An individual has a right to demand a guarantee of privacy of personal information stored on a computer.Give three such types of information.  (3mks)

20. a)  Give three comparisons of the traditional file management method of typing a document on a typewriter against using a word processor.     (6mks)

      b)  i) Define the term spreadsheet (1 mk)

            ii) Give two examples of spreadsheet packages available in the market today        (2mks)

      c) Explain the following terms as used in a spreadsheet:

             i)  What if …analysis         (2 mks)

             ii) Cell                (1 mk)

             iii) Formula  (1mk)

             iv)  Pie chart                                                                      (2 mks)

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

Trojan (horse); a program which misleads the user into thinking it is another

piece of software which, when run, executes another program;

Spyware; a program which records data such as usernames and passwords on

a host system and forwards the information to a third party;

Adware; code embedded or attached to program files which will persistently

show adverts (that attempt to generate revenue);

Worm; code which will run autonomously and replicates itself on a host system;

Ransomware; a program that encrypts user’s data to make it unreadable until

they pay for the key;

Remote Access Tool (RAT); allows access to control and monitor a computer

from a remote network location;

Rootkit; malware that has managed to gain ‘root’ admin privileges;

Bots/Zombies; a program installed on a computer that performs a job for the

remote owner of the bot/zombie such as sending spam or sending web requests

to perform a DOS or attacking a computer system;

Scareware; malware that tells you something is wrong with your system in an

attempt to get you to make a purchase;

Keylogger; a program that monitors/records a user’s keystrokes in order to steal

passwords/confidential details;

Open source : refers to software provided freely with its source code. The user can modify and redistribute the software.

Freeware: these are software that can be downloaded for free and distributed, buta  the source code is hidden and cannot be altered.

Shareware: is software that is available for free within a given trial period, after which it must be bought.

Proprietary: software made for commercial purposes. The source code is hidden, and it can only be used after paying for a licence.

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

(a) Defragmentation software   -   Reorganises files on a disk to improve efficiency

(b) Disk contents analysis/repair software - Scans a hard disk to identify bad sectors

(c) Disk formatter -  Prepares a hard disk for first use

• backups/dumps of files
• copy of files on CD/tape streamer
• file generations

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

• It is a program written in a high level langauage

• car factories/factories
• chemical/nuclear factories
• production lines
• warehouses
• deep in the ocean/down mines
• on other planets/in space
• road junctions

• Implementation

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

A primary key is a table field that uniquely identifies each record and ensures that duplicate entries are not allowed

A foreign key is primary key of a parent table placed in a child table to ensure that any record added to a child table is related to the one in parent table.

A foreign key is a field (or a set of fields) in one table that refers to the primary key of another table. It is used to establish and enforce a link between the data in the two tables, ensuring referential integrity.

Memory management

• Manage the computer’s memory;
• It can control which parts of the memory are being used by which process

Processor management

• Manage the computer’s processor(s)CPU;
• Schedules of which processes are to be executed;

Input/output management

• Manages input/output devices;
• Interacts with/manages/handles the (automatic) installation of device drivers;
•  Handles peripheral device interrupts;
• the computer can communicate with the outside world;
• Control network communication;
• Allow devices to send and receive data;

Managing storage

• Manage secondary storage devices;
• Loading data and programs into the computer’s memory;
• Storage space management (disk quotas);
• To ensure that storage space is allocated fairly and efficiently to specific tasks\users;

Managing security

•  User authentication;
• To make sure that users must prove who they are to access the system;
• Protect against malware;
• Block access to specific vulnerable operations or system areas. For example, software can only be installed with admin access;

Managing applications

• Control access to applications;
• Prevent users or processes from using unauthorised programs // allow users or
• processes to use authorised programs;
• Control application access;
• Prevent/allow an application access to data (or devices);

• user changes his mind
• new government legalisation/company policy company changes
• changes in hardware
• changes in software/upgrades/new versions
• improved operating efficiency/ease of use