The exam board expects you to be able to:

What is a computer system?

"A Computer System is a combination of componenets designed to process and store data. It comprises: at least one input device; a processing unit; an output device; a storage device and may contain a communications device".

A computer system is made up of hardware and software componenets and is capable of:

It may also be capable of:


The physical parts that can be seen, such as the monitor and systems case.


Programs made up of sequences of instructions that tell the hardware what to do.

Basic Computer Model - Concept

The basic model of a computer system is built on inputs, processes, storage and outputs:

Although this model applies to a personal computer, you should realise that it also applies to other equipment which uses computer technology, such as mobile phones, games consoles, mp3 players and so on.

What is hardware?

Hardware refers to any component that has a physical presence and can therefore be touched. Hardware devices can be divided into five types:

Input Devices - these include any kind of device which can be used for getting data into the computer system from the outside world. Some examples include: keyboard, mouse, microphone, heat sensors, switches, touch screens, digital cameras, scanners and so on.

Processing Devices - this usually refers to the Central Processing Unit (CPU) which carries out program instructions.

Storage Devices - these include any device which will store data until it is needed for processing. This can include temporary storage devices, like the computer's memory (RAM), or long-term storage devices (ROM) like hard-drives, DVD drives or tape drives, etc.

Communication Devices - these deal with the transfer of data from one computer system to another and include routers which link networks and modems which allow computers to communicate data via the Internet. For example: Modem, Network card, WiFi card, Router, Bluetooth devices, Infrared devices.

Output Devices - these include any devices which can provide data in a useful format to a user. For example: computer monitor, speakers, printer, headphones, LED, buzzer, motor or servo.

Peripheral Devices

These are hardware devices which fit into one of the above categories but are external to the main body of the computer. They are typically connected by cables (USB, Network, Firewire etc.) or wirelessly (Bluetooth, wireless network links etc.). Examples include keyboards, mice, scanners, webcams, printers, external hard-drives etc.