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.