was a version of the
Unix Operating System , licensed by
Microsoft from AT&T in the
1980s . The
Santa Cruz Operation (SCO) later acquired exclusive rights to the software, and eventually began distributing it as
SCO UNIX .
]]
Xenix was
Microsoft 's version of Unix intended for use on
Microprocessor s, but they called it Xenix because it could not license the "UNIX" name.
Microsoft purchased a license for
Version 7 Unix from
AT&T in
1979 , and announced on
August 25 ,
1980 that it would make it available for the
16-bit microcomputer market.
Xenix varied from its 7th Edition origins by incorporating elements from
BSD , and soon possessed the most widely installed base of any Unix flavour due to the popularity of the inexpensive
X86 processor, even though the port created for
Tandy Corporation computers proved to be more robust.
When Microsoft distributed Xenix, they did not sell it directly to end users; instead, they licensed it to computer manufacturers who then
Ported it to their own proprietary
Computer Architecture s. Microsoft Xenix originally ran on the
PDP-11 ; the first
Port was for the
Zilog Z8001 16-bit
Processor .
Altos shipped a version for their computers early in
1982 ,
Tandy Corporation shipped one for their
68000 -based systems in January
1983 , and
Santa Cruz Operation (SCO) released their port to the
Intel 8086 processor in September
1983 . A port to the 68000-based
Apple Lisa also existed. At the time, Xenix was based on AT&T's
UNIX System III .
Version 2.0 of Xenix was released in
1985 and was based on
UNIX System V . An update numbered 2.1.1 added support for the
Intel 80286 processor. Subsequent releases improved System V compatibility.
When Microsoft entered into an agreement with
IBM to develop
OS/2 , it lost interest in promoting Xenix. In
1987 Microsoft transferred ownership of Xenix to
SCO in an agreement that left Microsoft owning 25% of SCO.
In
1987 , SCO ported Xenix to the
386 processor, a
32-bit chip. Xenix 2.3.1 introduced support for i386,
SCSI and
TCP/IP .
Microsoft continued to use Xenix internally, submitting a patch to support functionality in UNIX to AT&T in
Minicomputer s extensively within their company as late as
1992 .
In the late
1980s , Xenix was, according to
Samuel J. Leffler ''et al.'' in ''The Design and Implementation of the
4.3BSD UNIX Operating System'' (
1989 ), "probably the most widespread version of the UNIX operating system, according to the number of machines on which it runs" (p. 7).
SCO branched Xenix into
SCO UNIX in
1989 . In the meantime, AT&T completed its merge of Xenix, BSD,
SunOS and
System V into
System V Release 4 . SCO UNIX was still based on
System V Release 3 , but had most features of Release 4. The last version of Xenix itself was 2.3.4.
