1. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Types of Operating System Unit 3 Section 4.1

2. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Types of operating system There are many different types of operating system. Some of the different types are: interactive, real- time, network, mobile device, embedded, desktop, server. They are not all mutually exclusive, e.g. you can have an operating system that is real-time and also embedded.

3. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Interactive operating system The user interacts directly with the system. The user supplies commands and data. The results of processing are given to the user immediately. The user and the computer are in two-way communication. The operating system on your computer at home is likely to be an interactive OS.

4. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Real-time operating system When an input is received it is processed in a timely manner. If no input is received in time then a time out will often happen and a default value will be used for the input. The output can affect the source of the inputs, so has to happen quickly enough for this to be possible. They normally need to be able to cope with multiple inputs happening at the same time. The Eden Project in Cornwall uses a real-time operating system on the computers used to monitor and control the environment in the greenhouses.

5. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Network operating system This is a layer of software that is added to the operating system of a computer. It allows a computer to be connected to a network. It intercepts all commands that reference resources elsewhere on a network and redirects the request without the user knowing it is happening. In other words, it allows you to connect your computer to a network without you having to know how the network itself works.

6. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Server operating system This is an OS that provides a specialised service to client machines on a network. Examples of services that may be provided include file storage, running applications, printer management and domain control. This specialisation results in a much better performance that could be achieved by a server conducting more general purpose processing.

7. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Desktop operating system A general purpose operating system. Allows a user to carry out a large range of tasks and are very complex pieces of software. They tend to be written in a modular fashion to allow for easier updates. They take up a large amount of memory and take a while to load.

8. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Embedded operating system An embedded operating system is one that is placed inside a larger machine for the purpose of controlling that machine, e.g. a computer inside a DVD player. Inputs often come from sensors; outputs are usually actuators. They generally have no user interface (or a very limited one). Operating systems for these devices need to work with limited memory and processing power

9. Section 4.2 AQA Computing A2 © Nelson Thornes 2009 Mobile device operating systems Mobile devices – like PDAs, mobile phones, mp3 players – need an operating system. They often need to work in real time to cope with multimedia applications. Processing power and memory on these devices can be quite limited. They may need to cope with maintaining a network connection that can vary in strength due to the mobility of the device.