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Operating System



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

Operating System



“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, SOLARIS, CP/M etc.

An operating system can be classified as follows:

  • Multi-user: Allow two or more users to run programs at the same time. Some operating system permits hundreds or even thousands of concurrent users.
  • Multi-Tasking: Allows more than one program to run concurrently.
  • Multi-processing: Supports running a program on more than one CPU.
  • Real-time: Response 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.


Functions of the operating system

It is responsible for managing all the resources attached to a computer system. These resources are the processor and various input and output devices.

  • Processing the commands
  • Controlling the execution of various programs
  • Managing devices ( like storage and retrieval of files on the disks)


The function involved in the management of resources is classified as follow:

  • Process Management
  • Memory Management
  • Input/ Output Management
  • Information Management
  • User interface


MS-DOS

  • The term DOS stands for Disk operating System
  • It is the Microsoft Disk operating system, developed by Microsoft for Microcomputers
  • MS-DOS was written by “Tim Patterson” in 1981 Microsoft.
  • MS-DOS was not designed to be a multi-user or multi-tasking operating system.
  • MS-DOS 6.22 was released in June 1994 and it was the last official stand-alone version released by Microsoft.
  •  It is the only OS, which can be loaded in the main memory of the computer, using a single disk.
  • It is a single-user operating the system, which allows only one user to work on a CPU at a time.
  • It is a powerful OS that is easy to use and handle errors effortlessly.
  • DOS has a character user interface (CUI) i.e. communication between a compute and the user is through characters ( a, b,c,1,2,3 etc.)
  •  In DOS, one has to key in the commands on the prompt. Prompt is a


C:/>
Or
C:\ WINDOWS\>
  • The mark (-) is the cursor which indicates that the command can be typed over here. This cursor keeps blinking on the screen.



Features of DOS

  • DOS is not a case sensitive i.e. DIR and dir are treated as the same
  • While typing a command, if you get “Bad command or file name” request. It indicates that DOS didn’t find a name matching your request. So, correct your command and enter it again.
  • It doesn’t support space entries in the file name.