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Function of Operating Systems. Introduction
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Function ofOperating Systems
Introduction
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The Operating System MUST:• provide and manage hardware resources
• provide an interface between the user and the machine
• provide an interface between applications software and the
machine
• provide security for the data on the system
• provide utility software to allow maintenance to be done
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IO Functions• input-output control system
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EvolutionNow higher level languages are developed, the OS needs:
• A translator program with:
• Assembler (translates assembly language)
• Compiler (translates high level language)
• Interpreter (translates then runs 1 line at a time)
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Memory Management SchedulingThe OS must manage the CPU time so that the user has no
concept of tasks being dealt with individually.
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Memory Management SpoolingThe I/O phase should not hold up the CPU which can easily
happen when mechanical operations cannot keep up. Eg??
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Memory Management - LoaderWhat happens if you load programs in a different order?
The ‘Loader’ remembers.
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Memory Management - UsersWhat happens if two users want to
use the same program at the same
time?
Programs such as this compiler,
working in the way described, are
called re-entrant.
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KEY TERMS• Memory Management - The process of the operating system
being able to control the use of the computer’s memory,
rather than the user doing it
• Scheduling - When there is more than one thing which could
be done at a time something has to decide what will be done
first.
• Spooling - store all input and output on a high-speed device
such as a disk until the slower peripheral device is ready.