KCSE Revision Resources

Explain how the operating system performs job/process scheduling/management

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

What is utility software?

System software that analyses, configures, optimises and maintains a computer system

Why must operating system be installed in a computer before any other program

Operating system manages the computer hardware thus without it the programs cannot communicate directly to the hardware
Provide a user interface through which a user can give instructions to the computer. Without a user interface, it would be difficult to load or run programs
other programs depend on the operating system to load them into the memory , allocate resources and schedule processor time, Without operating , there would be nothing to co-ordinate the execution of multiples programs
The OS organizes data in files and directories, making it possible for programs to save, retrieve, and modify data.
Without it, programs wouldn’t know where or how to store data.
The OS controls access to files, memory, and devices, ensuring that one program doesn’t interfere with another.

Which files are backed up in an incremental backup scheme?

Any new or changed files since the last backup

Identify and describe four roles of the operating system when managing the resources of a personal computer.

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

State Examples of utility programs

Encryption software

Scramble/encode/mix up data so it cannot be read/understood if intercepted/stolen

Defragmentation s/w

Move free space together and Move files together hence enabling Faster access to files

(Data) compression s/w

Reduce the file size of files or makes files smaller inorder To use less storage space
enables Faster transmission
enables storage of more files

Anti-virus / anti-malware s/w

To help protect computer/data against viruses/malware
To scan the computer to look for/quarantine/remove viruses/malware

Disk analysis and repair s/w

Scan disk and look for faults
Prevent the loss of data due to faulty disk

Auto-update

Checks Internet for new versions of software/OS
Downloads and installs without user interaction

Firewall

Examine incoming and outgoing traffic
To help restrict/prevent unauthorised access over a network

 ...over a network/external source

(b) The computer needs an operating system and utility software.

(i) The operating system controls the scheduling of processes.

Describe how the operating system uses scheduling to allocate processor time.

All processes are held in a queue

Processes are prioritised

Processes are switched On each clock cycle

Describe four features of the operating system when providing a graphical user interface on a personal computer. Give a suitable example of each feature.

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’

State ways of identifying illegal copies of an operating system

No licence agreement as a certificate of authenticity

Prices that are extremely cheap

No documentation manual

when one connects to the internet for authentication, the report from the manufacturer indicates that the user may be a victim of software counterfeiting

frequent runtime or occurrence of fatal errors when using the machine

Describe how the database can be recovered from a system failure

backups/dumps of files

copy of files on CD/tape streamer

file generations

Describe two possible causes of computer failure. In each case state how it could have been prevented

Hardware failure
Corrupted software files
Hacking into the system
Power failure

Social engineering is where someone is tricked or manipulated into providing secure information or access to a secure system. Describe each of the following social engineering techniques.

Blagging

This is where a victim is tricked/persuaded by a fraudster to give their details or payment information for a false reason/purpose;

Phishing

This is where the victim receives and responds to communication that appears to be from a valid or known source but is in fact fraudulent. (It allows the fraudster to capture private information before the victim realises);

Shouldering

This is where someone watches and records\remembers a victim entering their pin or security information such as passwords. (They can then use this information to gain access to a system)

List two types of disaster recovery tools.

online storage

incremental backup

full backup

RAID (level 0, 1, 10)

uninterruptible power supply (UPS)

What is data encryption?

Refers to the scrambling of data into unreadable form before transmission over a telecommunication media OR

transformation of data from plaintext to ciphertext

Briefly describe the information Security principles or CIA triads

confidentiality - The principle of protection from unauthorized access or disclosure

Integrity - the principle of ensuring that unauthorized or undetected changes to data or system configurations do not occur.

Availability - the principle of ensuring that data and services remain accessible to authorized users at all times

Confidential information about the students is to be stored on the computer system. Explain the measures that can be taken to ensure that such information remains confidential.

- Passwords
- Hierarchy
- Only allow some staff to access student files
- Only some machines able to access
- Physical location of these machines
- Physical lock on machines
- Encrypted data in files
- Firewall if connected to the Internet

State two effects of a computer virus

memory used up/slows down computer/alters setting/systems failure

erases files/erases data/corrupts data/data needs restoring

infects other computers on the network

production loss/financial loss

State two ways of protecting computers against viruses.

do not allow outside floppy disks/CD’s/DVD’s

use disk free work stations

download/install and use anti virus software

scan hard disks regularly

update the anti virus program regularly

do not open file attachments from unknown sources/download

doubtful software from the Internet

do not use files that come from unknown sources

buy original software/do not buy pirated software

use firewalls

Define Data Security

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

State two data protection rules that should be obeyed by all staff in a hospital.

data must be accurate/up-to-date

personal data must be registered

data must be used for the purpose that is registered for

if data is to be used for another purpose the registrar must be notified/

subject gives consent

patients must be able to see the data and have it changed if it is incorrect

processed fairly and lawfully

kept no longer than needed

kept secure

not transferred to other countries without protection

Q&A-KCSE Computer Studies Paper 1

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