@Quentin North (was: Re: Xenix)
Xenix was actually licensed by Microsoft from AT&T in the late 1970s. From what I remember it was the standard PDP11 Version 7 Unix source code, and distributed un-modified by Microsoft. MS was just the middle-man, getting into an aspect of the business that MaBell wasn't interested in. However, MaBell decided to "jealously guard" the UNIX[tm], thus the Xenix name.
SCO ported it to the IBM PC's 8086/8088 architecture in roughly 1983. Most of us yawned ... although looking back, it was a pretty good hack by SCO!
Before SCO's port was released, there was a TRS-68000 version, a Zilog Z8001 port, and an Altos 8086 version (not necessarily in that order, my mind is concatenating time). Microsoft didn't write any of them, rather the third-party companies in question did the coding. Microsoft was just the go-between for MaBell, who didn't want to get into that side of the business.
Seems to me I once saw an Apple Lisa running Xenix, not certain who did that port. Can anyone jog my memory?
 It's a technical term. Look it up.
 Not the same SCO as in the original article ... not by a long stretch.