Computer Hardware and Software

The computer system

A computer is an electronic device that accepts data, processes it under instructions, stores it and produces information. A complete computer system has hardware, software and the user. This topic is part of the Kenyan Senior School CBC (KICD) Computer Studies pathway.

Information processing cycle

Input, processing, output, storage. For example, typing marks (input), calculating the mean (processing), printing a report (output) and saving the file (storage).

Hardware

Input devices send data to the computer: keyboard, mouse, scanner, microphone, webcam, touchscreen, barcode reader.

Processing devices: the CPU has the control unit (directs operations), the arithmetic logic unit (calculations and comparisons) and registers (tiny fast memory).

Memory

• RAM - temporary, volatile working memory.
• ROM - permanent, non-volatile; holds start-up instructions.
• Cache - very fast memory near the CPU.

Output devices present results: monitor, printer, speakers, projector, plotter.

Storage devices keep data permanently: hard disk, SSD, flash disk, memory card, optical disc.

Storage units: 8 bits = 1 byte; 1 KB = 1024 bytes; 1 MB = 1024 KB; 1 GB = 1024 MB; 1 TB = 1024 GB.

Software

System software manages the computer:

• Operating system (Windows, Linux, Android, macOS)
• Utility programs (antivirus, disk cleanup)
• Device drivers (let the OS use printers and other devices)

Application software performs user tasks:

• Word processors (letters, essays)
• Spreadsheets (budgets, marks analysis)
• Presentation programs (slides)
• Database programs (records)
• Browsers and email clients

Functions of an operating system

• Manages memory and processes
• Controls input and output devices
• Provides a user interface
• Manages files and security

Care and safety

Keep the lab dust-free, use surge protectors, avoid food and drinks near computers, and update antivirus software. Sit with good posture to avoid strain.

Worked example 1

How many bytes are in a 2 KB file? Answer: 2 x 1024 = 2048 bytes.

Worked example 2

A teacher types, prints and saves a timetable using Microsoft Word. Name the hardware and software used. Answer: Hardware: keyboard (input), monitor and printer (output), hard disk (storage). Software: Word (application) and Windows (system).

Try it

• List five input devices found in your school lab.
• Differentiate between RAM and a hard disk.
• Convert 3 GB to MB.
• State two functions of an operating system.