Operating system

A Computer uses its components and peripherals to carry on computing and various other operations. The device called hardware requires instructions to work as they cannot work by themselves.

The memory has to be managed, I/O operations have to be managed and various other functions have to be done. These operations are performed by giving necessary instructions; the instructions are given in machine understandable form.

A common program is required which is capable to do such common tasks, so the development of Operating system came to being. Operating System acts as a mediator between the user and the hardware.

It is responsible for the smooth and efficient working of the computer system. It manages all the resources of a computer like memory, CPU, I/O devices etc. So it is also called Resource Manager.

Components of Computer System:

As figure depicts that operating system directly controls computer hardware resources. Other programs rely on facilities provided by the operating system to gain access to computer system resources.

Services Provided By Operating System:

An Operating System performs large number of function. Each function is carried out by a component of the operating system. The components functions of an operating system are:-

• Process Management
• Memory Management
• File Management
• Device Management
• Security and Protection
• Job Sequencing
• Error Handling
• User Interface

Process Management:

Any program which is in execution is called a process. Operating System of a computer manages the creation and deletion of a process, scheduling of various system resources to different processes requesting them and provides mechanism for synchronization.

Memory Management:

The operating system manages the main memory of the computer system. It takes care of the allocation and deal location of the memory space to the various programs.

File Management:

The operating system is the custodian of the files and files related activities such as file organisation, storing, naming, sharing and protection of files. It allows certain programmers to use a set of operations which characterize the file abstraction and hence makes the programmer free concerning the details of space allocation and utilization of secondary storage devices.

Device Management:

The operating system manages all the input and output devices. It keeps the track of requests of processes from input/output devices, issues commands to the input/output devices and ensures that correct data transmission is taking place to and from the input/output devices.

Security and Protection:

The computer stores large number of data, which is highly sensitive and valuable to the users. The operating system ensures that the security of the system data is maintained hence protects it against destruction and un- authorised access.

Job Sequencing:

Operating system helps in automatic job sequencing. It is the duty of operating system to ensure that the jobs entered in the computer are executed automatically in the given sequence.

Handling Errors:

Operating System handles errors as and when they occur and provides correction routines to remove them. The efficiency of an OS and overall performance of computerise measured by two factors:

§  Turn Around Time: The Time interval between the time user submits his job to the system for processing and the time when he receives the result (also called Response Time) . It is very important when multiple users share the same system.

§  Throughput: The total volume of work performed by the system over given period of time. Different OS like Single OS, Multi-user OS, Distributed OS, and Parallel Processing OS have been developed.

User Interface:

The main function of an operating system is to promote users with an interface to interact with computer system. It provides an easy to use interface to access the computer system through a combination of keyboard and mouse using menus, screens, commands etc.