OS-Unix -History and Features

UNIX -HISTORY
  •  Uniplex Information Computing System operating system
  •  Developed at bell laboratories
  •  Designed by ken Thomson in the late 1960’s
  •  Unix has been chosen since it is powerful, multiuser, multitasking system. Actually unix was derived from Multics.
  •  Around 1973, unix was rewritten using c by Dennis Ritchie.
  •  Around 1976, Unix version 6 was released outside bell labs.
  •  In 1979, AT&T issued a new version called the unix time sharing system version 7, which supports large files & came with a new extended version of c and a new shell.
  •  In 1980, Microsoft issued its own version of unix called xenix. In other development university of California developed unix for distributed system with the version no 4.1 BSD(Berkeley s\w distribution)
  •  By 1982, AT&T offering is system V release 4(SVR4)
Standards related to Unix are

AT&T system v interface definition(SV 10)
  •  Published in 1985 – supports system calls, library routines & utility specifications.
  •  POSIX – Portable Operating System Interface, defines interface between the unix kernel and the c language.
  •  XPG3 – x\open co ltd defines a common application environment for unix called XPG3.
  •  ANSIC – standards based on interface definitions for c program system.
Features of unix

Unix is a powerful multiuse multi tasking system.
  •  supports rich set of program developed aids like c compiler, make compiler construction tool like yacc & lex etc..
  •  text formatting tools like textedi toss : vi, & emacs, document : nroff & troff.
  •  E – mail.
  •  Source code maintenance system.
  •  Implemented widely using c hence portable to wide range of computers.
  •  Simplified treatment of file & device occurs.
  •  User interface for programmers & online users.
  •  Supports highly recurred access of information.
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