What is Operating System?

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      An Operating System is a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer hardware. In other words “The software that controls the hardware”. Some examples of operating systems are UNIX, Mach, MS-Dos, Ms-windows, Windows/NT, OS/2, MacOS, VMS, MUS and VM.

     An Operating system exploits the hardware resources of one or more processors to provide a set of services to system users. The operating system also manages secondary memory and I/O devices on behalf of its users. Controlling the computer involves software at several levels. We will differentiate kernel services, library services, and application-level services, all of which are part of operating system. Process run Application, which are linked together with libraries perform standard services. The kernel supports the processes by providing a path to the peripheral devises. The kernel responds to service calls from the process and interrupts from the devices. The kernel responds to service calls from the processes and interrupts from the devices. The core of the operating system is the kernel, a control program that functions in privileged state (an execution context the allows all hardware instructions to be executed) reacting to interrupts from external devices and to service requests and traps from processes. Generally, the kernel is permanent resident of the computer. It creates and terminates processes and responds to their request for service. Operating systems are resource managers. The main resource is computer hardware in the form of processors, storage, input/output devices, communication devices and data.


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معلومات عن التدوينة الكاتب : Unknown بتاريخ : السبت، 29 سبتمبر 2012
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