KCSE Revision Resources

Define disk formatting and state three reasons for formatting a disk

Definition

Disk formatting is the process of preparing a data storage media for initial use

Reasons:

To make a disk blank for reuse
To make it compatible with another operating system
to create tracks and sectors for first time use

State three features of a typical operating system

- (provides) user interface
– input/output control
– security
– handling interrupts
– spooling
– memory management
– processor management
– utilities (e.g. copy, save, delete, re-name, etc.)
– maintain user accounts
– load/run software
– error reporting/handling
– multiprogramming
– batch processing (JCL)/real time processing
– multitasking/multiuser/multi-access
– file management

State ways in which an OS secures a computer system

Access Controls: Authentication of users in order to access files

Performing regular patches of updates

creating secure accounts with required privileges

scrutinizes all incoming and outgoing packets of data through a firewall

encryption of data, during transmission

Log files to detect any breach

Describe two different functions performed by an operating system

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);

Give two reasons why some microprocessor controlled devices do not require an operating system

They run only one program/task

OS would increase development and manufacturing cost as more storage will be needed

Define patch as used in the operating system

Refers to a small piece of software designed to update, fix, or improve a specific part of the operating system or an application.

NB: Patches are typically released by the software's developer or the operating system vendor to address security vulnerabilities, software bugs, or to add new features or enhancements

Shaneela is designing and coding a website. The files she creates will be stored on
a computer.
(a) File management is a function that an operating system performs.
Describe how an operating system organises files

The organisation of files is in a hierarchy/tree structure
A node is either a folder/directory/sub-folder/sub-directory or the file itself
The top node/folder/directory/drive is the root

Describe the following features of a graphical user interface:

(a) Pointer

(b) Desktop

(a) Pointer

A graphical object on a computer screen that responds to move movement and allows the computer user to select and execute commands in graphical user interface operating systems

(b) Desktop

It Is a special folder in the file system that is displayed when no other windows are open

a) What is an operating system? (1 mark)

b) Briefly explain any four functions of an operating system. (8 marks)

c) Describe each of the following data processing methods: [6 marks]

a) What is an operating system? (1 mark)

It is a system software that manages the computer hardware. It provides a platform for installation & execution of application software.

b) Briefly explain any four functions of an operating system. (8 marks)
Interrupt handling - When an interrupt occurs, the current state of the CPU is saved & the OS handles the request, after which the OS restores the previous state of the CPU & resumes the interrupted process.
Process scheduling - OS decides which process runs next & for how long.
Memory management - Ensures that each process has enough memory allocated to execute without interfering with other processes.
Error handling - OS provides a mechanism to detect & respond to errors such as segmentation faults, hardware failures, or invalid instructions.

Briefly describe the following

Multitasking - the capability of an operating system to enable users to run two or more programs at once on a single computer

Real time processing - data processing system 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

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

On-line processing - is that type of processing where the result of data processing transaction is available immediately

Explain the purpose of an operating system

provides an interface between the computer user and the hardware
Manages the allocation and deallocation of the CPU to processes.
manages Input-output devices by use of drivers

Compare and contrast CLI and GUI

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

What is a defragmentation software

It is a utility software that places file data in adjacent sectors to free up space for more data and reduce access time for files stored

Distinguish between application and system software

Application software refers to software that is designed to help the computer user to accomplish specific tasks

Examples of application software include; Internet browsers, word processors, spreadsheets, databases etc

System software is software that performs tasks needed to operate the hardware and provide services to other software

Examples Operating Systems, Networking software, utility programs(encryption, backup, disk defragmentation software, ...)

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

Q&A-KCSE Computer Studies Paper 1

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