What is Operating System?

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A Brief History of UNIX

by Narendra Patil

Contract Technical Writer

Email: narendra.patil.g@gmail.com

November 10,2013

In the beginning, there was AT&T.

Bell Labs’ Ken Thompson developed UNIX in 1969 so he could play games on a scavenged DEC PDP-7. With the help of Dennis Ritchie, the inventor of the “C” programing language, Ken rewrote UNIX entirely in “C” so that it could be used on different computers. In 1974, the OS was licensed to universities for educational purposes. Over the years, hundreds of people added and improved upon the system, and it spread into the commercial world. Dozens of different UNIX “flavors” appeared, each with unique qualities, yet still having enough similarities to the original AT&T version. All of the “flavors” were based on either AT&T’s System V or Berkeley System Distribution (BSD) UNIX, or a hybrid of both. During the late 1980’s there were several of commercial implementations of UNIX:

Apple Computer’s A/UX

AT&T’s System V Release 3

Digital Equipment Corporation’s Ultrix and OSF/1 (renamed to DEC UNIX)

Hewlett Packard’s HP-UX


Lynx’s Real-Time UNIX

NeXT’s NeXTStep

Santa Cruz Operation’s SCO UNIX

Silicon Graphics’ IRIX

SUN Microsystems’ SUN OS and Solaris

… and dozens more.

The Open Standards Foundation is a UNIX industry organization designed to keep the various UNIX flavors working together. They created operating systems guidelines called POSIX to encourage inter-operability of applications from one flavor of UNIX to another. Portability of applications to different gave UNIX a distinct advantage over its mainframe competition.

Then came the GUIs. Apple’s Macintosh operating system and Microsoft’s Windows operating environment simplified computing tasks, and made computers more appealing to a larger number of users. UNIX wizards enjoyed the power of the command line interface, but acknowledged the difficult learning curve for new users. The Athena Project at MIT developed the X Windows Graphical User Interface for UNIX computers. Also known as the X11 environment, corporations developed their own “flavors” of the UNIX GUIs based on X11. Eventually, a GUI standard called Motif was generally accepted by the corporations and academia.

During the late 1990’s Microsoft’s Windows NT operating system started encroaching into traditional UNIX businesses such as banking and high-end graphics. Although not as reliable as UNIX, NT became popular because of the lower learning curve and its similarities to Windows 95 and 98. Many traditional UNIX companies, such as DEC and Silicon Graphics, abandoned their OS for NT. Others, such as SUN, focused their efforts on niche markets, such as the Internet.

Linus Torvalds had a dream. He wanted to create the coolest operating system in the world that was free for anyone to use and modify. Based on an obscure UNIX flavor called MINIX, Linus took the source code and created his own flavor, called Linux. Using the power of the Internet, he distributed copies of his OS all over the world, and fellow programmers improved upon his work. In 1999, with a dozen versions of the OS and many GUIs to choose from, Linux is causing a UNIX revival. Knowing that people are used to the Windows tools, Linux developers are making applications that combine the best of Windows with the best of UNIX.

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5 comments on “What is Operating System?

  1. nice narendra…
    i hv one question that

    Various modern OS, which include Android, iOS, Linux, and Mac OS X, take their some of their roots from UNIX.
    Windows does not.

    • Technically, Linux doesn’t. It was written completely independent of any UNIX; that is, it does not contain any code that originally came from any commercial UNIX Distribution. As a result, Android, which uses a Linux kernel, doesn’t have any UNIX derivation. Does Linux base some concepts on Unix? Of course it does. it was designed to give a similar look and feel to *nix for x86 machines. It’s a good thing Linux hadn’t found the x86 variant of BSD at the time, or he might not have even started Linux! FreeBSD/OpenBSD are themselves based on the Berkeley Software Distribution, which comprises of both Linux and several Software tools that are to be used in conjunction with it. If somebody wants to get really in peoples face about security, don’t even bother with Linux- use FreeBSD. They actually do proper Security audits on all source changes and try to eliminate even the tiniest possibility of a problem. Of course it doesn’t make you inherently secure, but at least you can feel elitist compared to even Linux users. I strongly recommend it if you have a few spare afternoons and nothing to do but learn a few ins and outs of a new OS to give FreeBSD a try.

      To flesh out the Windows timeline…

      Microsoft was not an Operating System company. They just sold BASIC. But they got themselves the beneficial contract with IBM where they kept the software license for redistribution… they didn’t outright lie and say they had an OS for IBM PC, but they didn’t say they didn’t, either. They found a contender for that OS in QDOS.

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