What is Operating System?
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