Functions of an Operating System

An operating system is the system software that manages a computer's hardware and lets you use it, and it carries out five functions. Each function is a job the operating system does quietly in the background so that you, and the programs you use, can get on with things.

Function	The job it does	An action that shows it
User interface	Lets you control the computer and see what is happening	Choosing a game from a console's home menu with a controller
Memory management and multitasking	Shares out memory between programs and decides which ones run	Switching from a drawing app to a calculator and back, with your drawing still there
Peripheral management and drivers	Sends data between the processor and devices such as scanners and printers	Loading the driver for a barcode scanner plugged into a shop till
User management	Sets up accounts, access rights and security	A parent's account on a family tablet can install apps; a child's cannot
File management	Names, stores, moves and saves files	Keeping a film project's video clips in one folder and its sound effects in another

Many descriptions of a computer at work are really describing one of these five functions. Match the action to the job in the table, and give the reason too, because one action can involve two functions: opening a saved level in a game needs file management to find the save file, then memory management and multitasking to load it into memory so you can carry on playing. If the action is about who is allowed to do something, it is user management; if it is about setting up a device or passing data to it, it is peripheral management and drivers.

These five are roles carried out by the operating system itself, not five separate application programs that you choose to run. You never open "memory management" from a menu — the operating system is already doing it while your apps run.

Practise this