An operating system is a system programprogram: a list of instructions written in a programming language that controls and organises the general operation of the computer.

Operating system functions

In any computer, the operating system:

Windows Task Manager provides information about programs running on your computer

• controls the backing store[backing store: a computer's primary data store, ie the hard disk ] andperipheralsperipherals: a device that connects to a computer, eg a mouse, keyboard, printer or scannersuch as scanners and printers
• deals with the transfer of programs in and out of memory
• organises the use ofmemorymemory: Where a program or data is stored on a computer. between programs
• organises processing timeprocessing time: the time it takes for a processor to process an input and generate an output between programs and users
• maintains security and access rights of users
• deals with errors and user instructions
• allows the user to save files to a backing store
• provides the interface between the user and the computer - for example, WindowsWindows: Microsoft's branding that precedes the operating systems name, eg Windows 98, Windows XP, Windows Vista etc. VistaWindows Vista: an operating system by Microsoft and Apple OSXApple OSX:an operating system by Apple Computers. For more information, see the User Interfaces Revision Bite.
• issues simple error messages

In a larger computer such as a main frame the operating system works on the same principles.

Modes of operation

Computers can operate in many different ways requiring different and complex operating systemsoperating system: an interface between hardware, eg a computer, and the user.

Real-time processing

When the computer has to react within a guaranteed time to aninputinput: A systems block or component that activates a system. For example, this could be a switch or an LDR. In a manufacturing system in a factory, inputs might include materials, components, labour, research and development., a real-time operating system (RTOS) is used. For example, the engine management system within a car uses a real-time operating system in order…