Introduction of Operating System

AN INTRODUCTION TO OPERATING SYSTEM

An operating system is an essential component of a computer system. The primary objective of an operating system is to make computer system convenient to use and utilize computer hardware in an efficient manner.

An operating system is a large collection of software which manages the resources of the computer system, such as memory processor, file system and input/output devices.

The user of a computer not merely interacts with the physical hardware of the machine. He interacts with all three- a machine, a compiler and an operating system. The positioning of operating system in overall computer system is shown below:

Every operating system has a kernel or a nucleus which permanently resides in the main memory  of a computer to perform some of the basic functions of operating system and to access other portions as and when they are needed. 

The remaining parts of an operating system are normally stored in a disk ready to be loaded into the main memory when required and ordered to do so by the kernel.

Facilities provided by an operating  system are the following:

1.    Easy interaction between human beings and computers.

2.    Starting computer operation automatically when power is turned on.

3.    Loading and scheduling user’s programs along with necessary compilers.

4.    Controlling input and output.

5.    Controlling program execution.

6.    Scheduling processes.

7.    Managing use of main memory.

8.    Managing and manipulating files.

9.    Providing security to user’s jobs and files.

10     Accounting resource usage.

Operating system directly controls computer hardware resources. Other programs rely on facilities provided by the operating system to gain access to computer system resources. There are two ways by which we can interact with an operating system:

i.                   By means of operating system call in a program .

ii.                 Directly by means of operating system commands.

System Call- system Calls provide the interface to a running program and the operating system . User program receives operating system services through a set of system calls.