An operating system is a software program that controls the interior activities of the computer hardware and provides user interface. Whenever computer is switched on then Operating system (OS) is the first program loaded into the computer’s primary memory.
One of the most important functions of the operating system is to provide an interface between the user and hardware. This interface enables a user to use hardware resources powerfully.
Windows operating system offers a latest graphic based interface to the users and they can use mouse to perform a number of operations. It is also achievable to work on multiple windows at a time. Some operating systems are DOS, Linux, UNIX, Windows etc.
Operating System (OS) provides a number of services to application programs and users. Applications access these services through application programming interface. By using these interfaces, the application can request from Operating system, pass parameters and receive the results of the operation.
OS is a software program that enables the computer hardware to communicate and operate with the computer software. Computer and software programs are useless without Operating system.
When computers were first introduced the user interacted with them using command line interface, which necessary the user to perform a series of commands in order to work together with the computer and its hardware and software. Each computer is using a Graphical User Interface (GUI) operating system that is much easier to use and operate.
Operating system is divided into four classes which are below:
Single user Operating system: Single user operating is that operating system which allows one user to work on a computer at a time. Like DOS, Windows etc.
Multi user operating system: A multi user operating system is that operating system which allows multiple users to work on a computer at a time. Like Linux, UNIX, Windows 2000 etc.
Single Tasking Operating system: Operating systems which execute only single task or job or program at a time is known as single tasking operating system. Like DOS
Multi Tasking Operating System: Operating systems which execute multi task at a time are known as multi tasking operating system like OS/2, UNIX, and Linux etc.
An OS performs the following functions:
1. Processor Management: The operating system assigns processors to the dissimilar jobs that must be performed by the computer.
2. Memory Management: Operating system allocates the primary and secondary memory to the system programs, user programs and data.
3. Input and Output Management: It carries out input/output organization and assigns dissimilar input and output devices.
4. File Management: It manages file on different storage devices and transfers these files from one storage device to another. It also allows the files to simply changed and customized through the user of text editors.
5. Scheduling: Scheduling determines and maintains the order in which jobs are to be executed in the computer system.
6. Time sharing: It co-ordinates and assigns compilers, assemblers, utility programs and other software package to different users working on the computer system.
7. Security Management: It establishes data security and reliability.
The main functions of an operating system are below:
A. Resource Management like processor management, memory management and device management
B. Process management like Job scheduling, Task management
C. Data management like file management and input/output management
D. Security management