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From: dyer@spdcc.COM (Steve Dyer)
Newsgroups: comp.unix.xenix
Subject: Re: 386 Unix/Memory Models
Message-ID: <305@spdcc.COM>
Date: Sun, 11-Oct-87 17:10:18 EDT
Article-I.D.: spdcc.305
Posted: Sun Oct 11 17:10:18 1987
Date-Received: Mon, 12-Oct-87 22:49:09 EDT
References: <143@conexch.UUCP> <140@turnkey.UUCP> <295@spdcc.COM> <387@cimcor.UUCP>
Organization: S.P. Dyer Computer Consulting, Cambridge MA
Lines: 36

In article <387@cimcor.UUCP>, mike@cimcor.UUCP (Michael Grenier) writes:
> Ah, true, but XENIX 386 only support XENIX 286 binaries in their non COFF
> format. They do NOT run under UNIX 386. However, AT&T 286 UNIX and
> Microport 286 UNIX binaries *WILL* run on 386 UNIX wihout modification.
 
I'm still trying to figure out why this response was posted, since I was
specifically talking about XENIX, and not anything else, and 286 execution
was just a parenthetical remark to its handling of 386 memory models.  Anyway,
XENIX 386 supports XENIX 286 binaries.  I'm sure the final AT&T/ISC/Microsoft
XENIX will still support XENIX 286 binaries.  Whether it will eventually support
other 286 object formats remains to be seen, although I see no reason why they
couldn't do it.  Anyway, no one is arguing that if you already have a big
software investment in AT&T 6300+/Microport 286 binaries, you should go with
XENIX 386 in its current state.

> What happens when Microsoft drops XENIX in favor of UNIX per their new
> agrement with AT&T? As the pres. of Microport pointed out - No emulations
> are perfect!

I can't speak for Microsoft or SCO, but their track record is one of
complete upward compatibility (to a fault :-), one might add, as you look
at their implementations of semaphores, locking and shared memory
which try to accomodate both Xenix III and System V semantics...)

Microsoft isn't dropping XENIX as much as making sure that there will
no longer be a host of competing object formats, which, if anything, only
fragments the 386 UNIX market and weakens its growth opportunities.
To the extent that XENIX 386 and 386 UNIX are both SVID-compliant, and I
believe they are, there's shouldn't be any problem handling both COFF and
XENIX format 386 objects, and I would imagine that the final XENIX development
set will allow you to produce COFF object files; otherwise it wouldn't make
sent to use XENIX as a development tool for the entire 386 marketplace.
-- 
Steve Dyer
dyer@harvard.harvard.edu
dyer@spdcc.COM aka {ihnp4,harvard,linus,ima,bbn,m2c}!spdcc!dyer