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 Able to explain the 6 key functions of system software  Able to explain each using a suitable example  Identify three different system software interfaces

B the system when the computer is first switched on I communication with each other O of files on the hard disk M during multi-tasking A between tasks S, user and file permissions, handling errors

6 AQA ICT AS Level © Nelson Thornes 2008 booting up the system when the computer is first switched on

7 AQA ICT AS Level © Nelson Thornes 2008 managing memory during multi-tasking The operating system allocates processing time and memory to the various tasks that need to be carried out.

8 AQA ICT AS Level © Nelson Thornes 2008 allocating processor time between tasks While computers seem to be able to multitask, a single processor can only do one thing at a time. Dual and quad core processors behave as if the computer has more than one processor.

9 AQA ICT AS Level © Nelson Thornes 2008 controlling where data is stored on disk The operating system organises the storage and retrieval of data files from backing storage such as the hard drive. It keeps a directory of where the files are stored on disk. It keeps track of the free space on the drive so that files can be stored efficiently for faster retrieval.

10 AQA ICT AS Level © Nelson Thornes 2008 communicating with input and output devices The operating system needs to: interface with peripherals such as a mouse or printer handle interrupts – signals that need an immediate response, such as a mouse click to stop a file printing.

11 AQA ICT AS Level © Nelson Thornes 2008 system security, user/file permissions, handling errors,

The operating system also provides the user different interfaces, such as: Graphical User Interface 1 2 3