As I read in Wikipedia, Unix started as a revolutionary operating system written mostly in C allowing it to be ported and used on different hardware. Descendants of Unix is mentioned next, mostly BSD. Clones of Unix, Minix/Linux are discussed as well.

But what happened to the original Unix operating system?

Does it exist as an operating system any more or is it nothing more than a standard like POSIX nowadays?

Do note that I am aware of this answer but it has no mention of the fate of the original Unix beyond the derived works.

  • 3
    Lets see, I saw PDP-11 running AT&T Unix in a production environment in 1995... Jun 12, 2011 at 17:26
  • The SVG image Wikipedia displays on Unix article explains Unix's history perfectly. 1. en.wikipedia.org/wiki/Unix 2. en.wikipedia.org/wiki/File:Unix_history-simple.svg
    – anilmwr
    Jun 13, 2011 at 5:36
  • As answers point out Wikipedia does cover this. The question seems to have a false assumption that an os could go on without evolving. The various history traces discussed and graphed do show what happened to the original Unix.
    – Caleb
    Jun 13, 2011 at 8:53
  • Did you notice the mistake in the chart? Not perfect, more here. -1
    – user2362
    Sep 18, 2011 at 16:07
  • apt-cache search simh - Emulators for 33 different computers... then find the disk image of dmr... unix.stackexchange.com/questions/58660/…
    – ixtmixilix
    May 13, 2013 at 21:46

2 Answers 2


We can distinguish UNIX the trademark from Unix the code-base.


Unix was initially developed at Bell Labs, owned by AT&T. This Unix team became AT&T's Unix System Laboratories (USL) and produced Unix System V (Roman numeral for five) or SysV for short. The University of California at Berkeley (UCB) also licenced Unix for academic use, their Computer Systems Research Group (CSRG) later made many important changes and additions (notably TCP/IP) in their Berkeley Software Distribution (BSD) which were later incorporated into many descendants of Unix leading to the BSD vs SysV split. Ultimately a lot of the BSD changes were back-ported into SysV (which we can consider the main "ancestral Unix" code base).

Along the way, many different businesses have licenced this code-base (at various stages in it's development) and used it as the basis of their proprietary Unix operating systems - AIX, HPUX, IRIX, Solaris, Ultrix and dozens of others.

Novell (Attachmate)

USL was purchased by Novell. At this time, the ancestral Unix code was known as Unix system V release 4 - or SVR4 for short. Novell named their product Unixware to complement the name of their legacy network OS Netware. Novell have been Acquired by Attachmate.

The Santa Cruz Operation

Novell eventually sold their Unix business to an old SVR3.2 licensee The Santa Cruz Operation (SCO) whose main business up to that point was selling a product named OpenServer that was based on Unix SVR3.2. Novell (since bought by Attachmate) still own some rights‡ to Unix but do not do any work on the source code.

Caldera / The Sco Group / TSG Group Inc

The Santa Cruz Operation later sold their Unix business to a Linux company Caldera who later renamed themselves to The SCO Group (sometimes referred to as new SCO or SCOG) and who had a disastrous failure of leadership leading to chapter-11 bankruptcy and sale of the Unix business to UnXis, a business formed for this purpose. Subsequently The SCO Group were reorganised into TSG Group Inc and TSG Operations Inc. They have no role regarding maintenance of the ancestral Unix code base. In August 2012 TSG Group Inc converted to chapter 7 bankruptcy.

UnXis / Xinuos

So now UnXis are responsible for marketing and developing/maintaining Unixware - the ancestral AT&T Unix code base. Because the Santa Cruz Operation (old SCO) originally ported† Unix to the x86 platform, I believe x86 and x86_64 are the only target platforms that UnXis directly support.

On June 12 2013, UnXis announced it had been renamed Xinuos.

Xinuos no longer seriously support installation of their ancestral Unix products on bare metal. Their SVR3.2 and SVR5 based products are offered as virtual machines (VM) to be run under their "OpenServer 10" product which is a derivative of FreeBSD.

So the body of code with the greatest claim to be the prime descendant of the ancestral Unix code is now, in practical terms, not much more than a compatibility layer between other operating systems and legacy applications.

Microsoft licensed Unix and ported it to 16-bit Zilog Z8000 - old SCO purchased Xenix from them and ported it to the 16-bit 8086 architecture (used by IBM for their original IBM PC). Old SCO later ported SVR3.2 to x86 as 32-bit SCO-Unix later renamed OpenServer

Novell's rights were contested, somewhat futilely, by The SCO Group (now named TSG Group Inc), the bankrupt remnants of the old Linux company Caldera. It is not yet clear whether TSG Group Inc have finally discontinued this and related litigation, the last activity in a related case against IBM was January 2018 and TSG Group Inc are not commercially active

  • 1
    Exactly the answer I was looking for.
    – Oxwivi
    Jun 13, 2011 at 18:51
  • 2
    I think that the SCO-Linux Controversies, have somewhat quieted since suing IBM and Novell has largely failed. SCO, according to the Tenth Circuit's report, was rejected from appealing the case and the court ruled in favor of Novell.
    – new123456
    Oct 16, 2011 at 0:00
  • @new123456: I think the remaining parties are not "SCO" but TSG Group Inc and TSG Operations Inc who are in the hands of Edward N. Cahn, Chapter 11 Trustee. As I understand it, several sets of litigation are stayed pending resolution of the Chapter-11 bankruptcy process. As you say, not much of interest seems to be happening and the eventual final tidying up and closure may not be very interesting either. The answer above is primarily about identifying the trail of ownership of the ancestral Unix code-base not about the litigation. I'll tidy up the answer a little. Oct 16, 2011 at 11:05
  • 2
    Another company that you wouldn't nowadays associate with Unix - Microsoft (with Xenix).
    – PC Luddite
    Jul 1, 2016 at 17:34

UNIX® nowadays is a standard/certification.

Unix certification

Don't know exactly what you mean by the question, but this could be a proper answer.

  • The question is "Does it exist as an operating system any more or is it nothing more than a standard like POSIX nowadays?", and the standard is, in itself, not a Unix system.
    – Kusalananda
    Apr 30, 2020 at 10:22
  • The top level question is «What is Unix now?», so I think my answer is not irrelevant.
    – Krackout
    Apr 30, 2020 at 10:26
  • 2
    The title is not the question, it's a summary of the question. The actual question(s) to be answered are in the text.
    – Kusalananda
    Apr 30, 2020 at 10:27

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