Operating System


  • OS can be defined as an organized collection of software consisting of procedures for operating a computer.
  • OS provides an environment for execution of programs.
  • OS acts as an interface between the user and the hardware of the computer system.


2Operating system continues interacts with user in two ways.

  1. Operating system commands

    • Enables user to interact directly with the O.S

  2. Operating System calls

    • Provides an interface to a running program and the operating system . system calls in UNIX are written in ‘C’.


History of UNIX

  • Ken Thompson at AT & T Bell laboratories designed UNIX in late 1960’s.
  • Two versions of UNIX that emerged are AT & T UNIX and BSD Unix.
  • In 1989, AT & T and sun Micro Systems joined together and developed system V release 4(SVR 4)
  • Two of main standards mainly in use are POSIX and X/open standard. In 1988, MIT formed X consortium developed vendor _ natural X window system.


What is LINUX ?

  • An open source UNIX like operating system.
  • Initially created by LINUX Torvalds for pc Architecture ports exit for alpha and space processors
  • Developer community world – wide contribute to its enhancement and growth.


Features of UNIX  

  • Multi – User , Multi tasking, time sharing
  • Portability
  • Modularity
  • File structure
  • Security
  • Strong network Supporting & advanced graphics