HISTORY OF UNIX
Unix is the most popular operating on multi-user systems. This OS started – off as a single user system
on a cast – off DEC PDP-7 machine at Bell laboratories in 1969. Ken Thompson, with ideas and help
from Dennis Ritchie and others, wrote a small general – purpose OS which included utilities to manage
files and processes on PDP-7, among other utilities. The system developed attracted a large number of
enthusiastic users and was eventually transferred to a larger machine, the PDP-11/20.
In 1973, Thompson and Ritchie rewrote the UNIX OS in C, breaking away from the tradition of
writing Operating systems in assembly language.
Around 1974, UNIX was licensed to universities for educational purposes and a few year later, was
made commercially available MS-DOS was created much later than UNIX, by which time the industry
had begun to accept UNIX as the standard So the design of MS-DOS has therefore been influenced by
UNIX features.
Versions of Unix
The flexibility of UNIX. Which allows it to shaped to meet a variety of needs, has always been one of its
major attractions. Some of the popular versions of UNIX are:-
Version Developed By
UNIX SYSTEM AT&T
UNIX BSD (4.xx) Berkeley Software Distribution of Berkeley University
XENIX Microsoft for micros
ULTRIX DEC for minis
AIX IBM
FEATURES AND BENEFITS OF UNIX
The UNIX OS is available on machines with a wide range of computing power ranging from
microcomputers to mainframes, and on different manufacturer’s systems. This is due to the following
reasons:-
PORTABILITY
The system is written in a high – level language making it easier to read, understand change and
therefore, move to other machines. The code can be changed and compiled on a new machine.
MACHINE INDEPENDENCE
The system hides the machine architecture from the user, making it easier to write application that can
run on micros, minis and mainframes.
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