Microsoft's UNIX version. Earliest versions were based on System 7 UNIX and released in 1980. Later, Microsoft sold the system to SCO, where it became first SCO Xenix, then SCO UNIX, and in the 1990s, SCO OpenServer (which, according to those who have used it, stays firmly in the 1990s and won't budge without a massive investment.)

Even though I haven't used Xenix (many say this is just a positive thing), I might tell here about one big legend I've heard:

Xenix's fsck command, for some obscure reason, asks for scratch file name. Many sysadmins, upon confronting this problem, just write the filename that's printed just before this question - something like /dev/hdroot0...

"Must be a fast machine as fsck ran quick..."

- (ex-)sysadmin

Microsoft has continued this tradition of making intuitive user interfaces ever since... =)


Just to clear things up here... Xenix was the name of Microsoft's version of Unix. Yes, there was a Microsoft UNIX

Back in 1979, before MS-DOS was invented, Microsoft's main product was a Basic compiler. UNIX was the main OS in use at the time, so naturally, Billy G decided that he wanted to get his filthy paws on it. MS licensed AT&T's Unix, and combined it with BSD Unix to get Xenix, the first Unix for x86 architecture.

As MS-DOS' popularity sky-rocketed along with IBM's PC (1980 onwards), Xenix suffered a major drop in priority. Microsoft sold the rights to it to the Santa Cruz Organisation (SCO), who later renamed it to SCO Unix. For a most of the 80's, SCO Unix was one of the most popular Unices, but since then it has been overtaken by the offerings of hardware vendors, such as IBM's AIX, Sun's Solaris and Hewlett Packard's HPUX.

Recently, SCO have sold off their Unix division, UnixWare. It was bought by Linux vendor Caldera, who have hopes of getting full Unix branding for their Linux distro.

Some informations taken from Modern Operating Systems by Andrew Tanenbaum


XENIX was a Microsoft port of V7 UNIX to Intel 8086 processors and the IBM-PC, among other 8 and 16-bit systems. Most of AT&T's System III was merged in.

The name XENIX came from a provision in AT&T's early UNIX source license agreements, namely that a product could not be resold under the name UNIX. It appears to be meaningless.

XENIX was a smash hit, and at one time, was by far the most popular UNIX system in the world. As its popularity waned, it was sold to SCO, who continued to merge AT&T code into it and sold it as variously XENIX/286, SCO XENIX, SCO XENIX System V, SCO UNIX, SCO OpenDesktop, and finaly SCO Openserver. SCO UnixWare is an entirely different product and codebase, originally developed by Univel.

Rumor has it that Microsoft continued to use XENIX and common UNIX tools such as nroff and troff internally until 1989 or 1990, but I cannot find corroborating evidence.

The prospective XENIX user should be warned, it was a primitive system, even by the standards of the day. XENIX and XENIX/286 did not support memory protection due to hardware limitations. No product sold under the name SCO UNIX ever included TCP/IP. Finally, in the name of backwards compatibility, XENIX and its derivatives have always been subtly different in annoying ways from their UNIX brethren...

To be perfectly clear, SCO UNIX is a XENIX derivative, not the other way around.

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