Operating System


A program that acts as an intermediary between a user of a computer and the computer hardware.

Operating system goals:

Execute user programs and make solving user problems easier.

Make the computer system convenient to use.

Use the computer hardware in an efficient manner.

Operating system – controls and coordinates the use of the hardware among the various application programs for the various users.

Operating System

Need of Operating system

The primary need for the OS arises from the fact that user needs to be provided with

services and OS ought to facilitate the provisioning of these services.

The central part of a computer system is a processing engine called CPU. A system should make it possible for a user’s application to use the processing unit. A user application would need to store information.

The OS makes memory available to an application when required. Similarly,

user applications need use of input facility to communicate with the application. This is

often in the form of a key board, or a mouse or even a joy stick

Usage of Operating System:

  1. Easy interaction between the human & computer.
  2. Starting computer operation automatically when power in turned on.
  3. Loading & scheduling users program.
  4. Controlling input & output.
  5. Controlling program execution.
  6. Managing use of main memory.
  7. Providing security to users program.

Functions of Operating System :

The main functions perform by most Operating System of today are as follow: -

1. Process Management: – The process management module of an Operating System takes care of the creation & deletion of processes, scheduling of various system resources to the different process requesting them, & providing mechanism for synchronization & communication among processes.

2. Memory Management: - The memory management module of an Operating System takes care of the allocation & reallocation of memory space to the various program in need of this resource.

3. File Management: - computer use a lot of data & programs, which are, stored on secondary storage devices. File management functions of an Operating System. Involves keeping track of all different files & maintaining the integrity of data stored in the files including file directory structure.

4. Security: - The security modules of an Operating System protect the resources & information of a computer system against destruction& unauthorized access.

5. Command Interpretation: -The Command Interpretation module of an Operating System takes care of interpreting of user commands, & directing the system resources to handle the requests. With this mode of interaction with the system, the user is usually not too concerned with the hardware details of the system.

6. Input/Output or Device Management: - coordination & control of various input & output devices is an important function of the Operating System. This involves receiving the request for I/O interrupts, & communicating back to the requesting process.

7. Job Control: - When the user wants to run an application  program, he must communicate with the Operating System telling it what to do. He does this using Operating System job control language or JCL. JCL consists of a number of Operating Systems commands, called system commands that control the functioning of the Operating System.







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