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Operating systems is a program that acts as an intermediary between a
user of a computer and the computer hardware (H/W). The purpose of an
operating system is to provide the environment in which the user can execute
programs. The O.S. is a resource allocator (managers all resources, decides
between conflicting requests for efficient and fair resource use) and is a
control program (controls execution of programs ) to prevent errors and
improper use of the computer.
1.2 Computer System Components:
An O.S. is an important part of almost every computer system. A
Computer System can be divided roughly into four components:
1. The (H/W) (cpu, memory, I/O devices).
2. Operating system (O.S.).
3. Application programs (Assembler, data base, compiler, text, and editor).
4. The users (people, machines, other computers). See figure (1.1).