Functions of An Operating System
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The OS has four main functions. These are:
Storage Management
This includes both main memory, (immediate access storage), and backing storage.
To increase the throughput of data from memory to the processor cache memory can be used. Modern CPU's are now so fast that they have to slow themselves down to access RAM. The cache is an area of very high speed memory that is loaded with the instructions that the processor is using at that time. This is possible as most programs are sequential with only small loops in them.
Processor Management
The way in which the processor is utilised depends on the mode of operation. On single user machines the processor is dedicated to one job. On multi-access systems queues need to be kept of all the jobs.
Process Management
Many processes running in the same computer may, at times, come into conflict. They may want to use the same resource at the same time. The OS needs to break this deadlock if it occurs.
Device and File Management
The OS handles all input and output from/to peripheral devices. It attempts to give the user a device independent view to simplify the interface. Large systems may include 'spooling' facilities to allow a printer to be shared among a number of users.
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