Computer Systems

A computer system consists of hardware and software, along with any peripheral device required to operate it. Computer systems take a range of forms: personal computers (PCs), laptops, tablet devices, smartphones, televisions, control units in ovens or washing machines, onboard monitoring systems in cars, and programmable toys, to name a few.

However, despite this variety, they all conform to the following four steps, as set out by John von Neumann in 1945:

They receive information via an input.
They store this information for use in processing.
They process this information and store as required.
They output information.

An assortment of images of different domestic computer systems.

Examples of computer systems around the home.

Hardware components include inputs, processors, memory, a motherboard and outputs. It is the software programs which enable computer systems to be flexible in meeting a range of user needs. A program’s instructions are carried out by the processor. Inputs are required for information to be received by the computer in the first place. On programmable toys (such as Bee-Bots or Roamers®), buttons are used to input the commands. A desktop PC will use a mouse, keyboard and perhaps a camera and microphone. Laptops feature a keyboard and touchpad. Tablets and smartphones feature a touchscreen.

The motherboard is the main circuit board found in a computer system. The other hardware components are mounted to it and peripheral devices can be plugged into it via a variety of ports. The motherboard enables the transfer of data between components via “buses”, which pupils will learn about at Key Stage 3.

A photo of the motherboard of a Raspberry Pi computer.

There are various types of memory components, used to store information. Some store information temporarily as Random Access Memory (RAM) whilst that information is being used by the processor. Other components provide more-permanent storage, such as the hard drive. The information is stored in binary form – coded numerically using 0s and 1s. The amount of memory needed to store a file depends on its type and complexity. We measure memory capacity in “bits” and “bytes”. One bit is either a 0 or a 1. One byte comprises eight bits and can hold the binary code for one character – e.g. the letter A. There are 128 characters in the standard eight-bit set. One kilobyte (1KB) actually comprises 1,024 bytes, which would suffice to store a paragraph of 150 words averaging five letters each. One megabyte (1MB) comprises 1,024 KB, which might suffice to store a few images. One gigabyte (1GB) holds 1,024 MB, which might store a short video or a significant quantity of text – equivalent to 150 copies of the Q’uran and Bible!

A computer system with a dedicated function – be it a programmable toy or a car engine’s fuel-flow regulator – is typically constructed from a microcontroller, which comprises a processor and memory in a single computer chip. These are configured during construction. Some are ‘fixed’, such as those in electric razors, but others are programmable, including those in alarm clocks, central-heating systems and scientific calculators.

A photo of a microchip.

A microcontroller (microchip) combines both a processor and memory.

Once a computer system has processed information, it will output it to the user in several ways. The output on a programmable toy consists of the motors which cause the device to move. Typical outputs for a PC include the screen, speakers and printer.

The operating system (OS) software enables the various hardware components to communicate and function together and provides the user with an interface to operate the computer. There are different operating systems available for different computers. Amongst the most popular are Microsoft Windows, Windows Phone, OS X (for Apple computer systems), iOS (for Apple’s mobile devices), Android (for touchscreen mobile devices) and Linux (a free, open-source operating system).

The operating system enables application software programs to be installed. With such software, a computer system can perform specific tasks beyond the running of the computer system itself. Microsoft Office is a common piece of application software for word-processing, presentations and spreadsheets, and mobile phones run an increasing variety of apps. It is also possible to run programmer-development kits such as Scratch, Greenfoot, Visual Basic and JDK within an operating system. These enable programs to be created by the user.

Why are computer systems important?

From the alarm clock that wakes you, to the TV you watch of an evening, computer systems surround us all the time. They’re used in communication, transportation, industry, business, scientific research, education, sport, entertainment and media. The computer system likely to be the closest to you for the greatest amount of time is the mobile smartphone, on which you can install software for a wide range of apps enabling a multitude of tasks. You can configure your smartphone’s communication technology as a Wi-Fi (wireless local area network) hotspot, meaning that other computer systems can use it to access the internet whilst you’re on the move – a functionality referred to as “tethering”.

A diagram illustrating tethering.

What do computer systems look like in the Primary curriculum?

England’s national curriculum for computing states that Key Stage 1 children should understand how algorithms are implemented as programs on digital devices, including any computer systems used in the classroom (e.g. desktop PCs and programmable toys). From a young age, children are surrounded by computer systems both inside and outside school. As pupils tinker with a variety of devices, they start to understand their purpose and how to interact with them. Pupils spot similarities and differences across devices. Progressing through the Primary phase, they learn to select and use different computing systems with increasing awareness of their purpose. This includes selecting appropriate computer systems which may be programmed, such as the Bee-Bot in Key Stage 1 or a computer running Scratch in Key Stage 2. Pupils become more familiar with the general features of computer systems, understanding that a typical system has both inputs and outputs. They make links to the use of inputs and outputs in physical computing projects, and to the sharing of information across computer networks.

3 - 5 years

Pupils use a range of computer systems, including programmable toys, desktop PCs, laptops and tablet devices. They develop an awareness of how to interact with these, using a range of input types and observing a range of outputs, including movement, sound and visual signals. Peripheral devices used to control the computer systems may be modified to aid young pupils – e.g. large-button keyboards and mice.

5 - 7 years

Pupils’ proficiency using various computer systems grows and helps them understand how to implement algorithms as programs on a range of digital devices. They use a variety of inputs. The buttons on programmable toys allow directional commands to be entered. If using graphical programming languages such as ScratchJr running on tablet devices, they will manipulate these programming environments via the device’s touchscreen as they construct a sequence of commands to implement their algorithms.

7-11 years

Pupils learn that computer systems can be connected to form a network to share resources and that the internet consists of millions of computer systems connected around the world. The children take part in activities modelling the internet to learn how it provides services like the World Wide Web. They learn that computer systems exchange data via their inputs and outputs. They may use different computer systems with a variety of software, creating programs which utilise a variety of input and output devices. In a computer game, they might use the input of a keyboard or mouse to control an onscreen sprite with accompanying sound output. They might create programs which generate their outputs in response to a microphone or camera input, or even a tilt or distance sensor.

In the case of making a short film, pupils might use a tablet device featuring a camera to input (record) film footage. They might then transfer it to be saved on the hard drive of a desktop PC running application software for video editing. (So, they’ll be using an output on the mobile device to connect to an input on the PC.) They’ll develop an understanding of data-file size and its implications on project time and feasibility. Other outputs in this example are the video images on the PC screen and any audio coming through the speakers. To edit their films, the children will use the keyboard and mouse as inputs. The computer's processor may convert the finished video file into a form more suitable for viewing, which can then itself be saved, transferred, shared and even uploaded to a video-streaming website via an ethernet connection.

Find out more about computer systems / Downloads

Computing At School / Naace (2013): “Computing in the national curriculum – a guide for Primary teachers” (opens in a new window)

Wikipedia page on computer systems (opens in a new window)

Wikipedia page on software (opens in a new window)

Activities that are great to get you started:

These activities develop pupils' understanding of computer systems.

Bee-bots 1,2,3 Programming

Age:5-7 years (can also be adapted)
Concepts / Approaches: Programming, Persevering, Debugging, Algorithms
Curriculum Links: Maths

Pupils create a sequence of instructions to draw the shape of a numeral e.g. 3. Programming in this activity involves taking the algorithm and using it to program a Bee-Bot to navigate a route tracing out the shape of the numeral.

The Bee-bots 1,2,3 Programming has been rated 5 stars

Investigating Inputs Activity

Age:7-11 years
Concepts / Approaches: Computer Systems, Creating, Variables, Programming, Inputs, Collaborating
Curriculum Links: D&T

An investigation of different input devices, in which pupils are challenged to create programs that use the input from a device in a short piece of code.

The Investigating Inputs Activity has been rated 5 stars

Modelling the Internet

Age:9-11 years
Concepts / Approaches: Internet Services, Abstraction, Computer Systems, Computer Networks
Curriculum Links: Geography

Pupils learn that the internet is a vast network of computers and other devices connected across the world, as they explore the difference between the internet and the World Wide Web (WWW).