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What operating System do?




A computer system can be divided roughly into four components: the hardware/ the operating system, the application programs/ and the users.

The hardware - the Central Processing Unit, the memory and the input/output device provides the basic computing resources for the system. The application programs such as word processors/ spreadsheets/ compilers, and Web browsers-define the ways in which these resources are used to solve users' computing problems. The operating system controls the hardware and coordinates its use among the various application programs for the various users.




There are two kind of views a system have, which means an outer view and a view from inside of the devices - about its internal functionalities which tells about how process actually has been completed.

User View

The user's view of the computer varies according to the interface being used. Most computer users sit in front of a PC, consisting of a monitor/ keyboard/ mouse, and system unit. Such a system is designed for one user to monopolize its resources. The goal is to maximize the work (or play) that the user is performing.

Goals : 
                - ease to use.
                - complete resource utilization.

A user sits at a terminal connected to a mainframe or a minicomputer, other users are accessing the since computer through other terminals. These users share resources and may exchange information. The operating system in cases is designed to maximize resource utilization to assure that all available CPU time, memory, and I/0 are used efficiently and that no individual user takes more than her fair share.

System View

From the computer's point of view, the operating system is the program most intimately involved with the hardware. In this context, we can view an operating system as a resource allocator. A computer system has many resources that may be required to solve a problem: CPU time, memory space, file-storage space, I/0 devices, and so on. The operating system acts as the manager of these resources. Facing numerous and possibly conflicting requests for resources, the operating system must decide how to allocate them to specific programs and users so that it can operate the computer system efficiently and fairly. As we have seen, resource allocation is especially important where many users access the same mainframe or minicomputer. 

A slightly different view of an operating system emphasizes the need to control the various I/0 devices and user programs. An operating system is a control program. A control program manages the execution of user programs to prevent errors and improper use of the computer. It is especially concerned with the operation and control of I/O devices.




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