What is Operating System of a Computer?

Operating System

An operating system consists of a set of programs that controls, coordinates and supervises the activities of distinctive components of a computer system. Its function is to establish a link between the computer hardware and the user.

"An operating system is a software, or a series of programs, which performs various types of functions in order to manage and organize  files."

Some of the most commonly used operating systems are MS DOS, WINDOWS, LINUX, SOLARIES, CP/M etc.
Operating system can be classified as follows

Multi-user: It allows two or more users to run programs at the same time. Some operating systems permit hundreds or even thousands of concurrent users.

Multi-tasking: It enables more than one program to run concurrently.

Multi-processing: It supports running a program on more than one CPU.

Multi-threading: Allows different parts of a single program to run concurrently.

Real-time Processing: Responds to input instantly. They are used to control machinery,  scientific instruments and industrial systems, general-purpose operating systems, such as DOS and UNIX are not real-time processing.

FUNCTIONS OF OPERATING SYSTEM  

 Controlling the execution of various programs.
 Managing devices (like storage and retrieval of files on the disks).
 Process Management
 Memory Management
 Input/Output Management
 Information Management
 User Interface

COMMON OPERATING SYSTEM MS DOS 

 The term DOS stands for Disk Operating System developed by Microsoft for micro computers.
 DOS is a single user operating system.
 It has a Character User Interface (CUI) i.e., communication between a computer and the user is through characters.
 In DOS, one has to key in the commands on the prompt. Prompt is a place where commands are issued. It may look like

C:\>
or
C:\WINDOWS\>