[Smaug] Early Xenix history

Peter Belew abcruzww at gmail.com
Sat Nov 19 20:39:46 PST 2005

The original version of Xenix was created by Microsoft, apparently (and
as I remember vaguely), but was only sold OEM to other companies. And
the Microsoft version was only for a 8086/8088, so it was crippled by
lack of memory protection or mapping. One of the OEMs was SCO, I
think when they were still at their first office on Chestnut (at Lincoln or
Walnut) near downtown Santa Cruz. So SCO produced the first version
for the 286, with its clumsy segmented memory mapping.


Basically I think that Microsoft was very much distracted by the advent
of the IBM PC and the success of PC/MS-DOS and GW-BASIC in the
early '80s, and *NIX didn't look like it had much future on the '86 PCs of
the time.

It's clear Microsoft was interested in Unix features in early MS-DOS -
they made a big thing in early DOS of having a plan to make system
calls more 'Unix-like' for file system access. In fact they never followed
through with this concept in a good way; for example when you make
a file open call that's 'Unix like' (e.g. providing a full path in the file
parameter) what the call does internally is to use CP/M-style calls to
cd to the directory specified, open the file with a CP/M-style FCB file
open call, then CD back to the original directory - very klunky! (I once
traced through this garbage for a job I had, it was ugly!).

Of course, all this changed with "New Technology" (NT, W2K, XP, etc.).

I was a casual visitor to the old SCO office on Chestnut in the late '70s -
a UCSC student friend worked there, with the Michaels founders - but
soon got wrapped up in PC work elsewhere, though I was using a System V
system at work for cross-development of a PC OS for the Z8000 and
later porting of MS-DOS to my employer's PCs. (The System V system
was soon replaced with BSD - on PDP-11s and Vaxen). But none of
those were SCO systems, so I didn't follow the later details of SCO
history too closely.

(I'm starting a new thread with this posting - the other thread was getting way
off topic. But I can see this thread going in different directions already!)


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