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From: davidsen@steinmetz.UUCP (Davidsen)
Newsgroups: net.micro.pc,net.unix
Subject: Re: UNIX for 286-based systems
Message-ID: <782@steinmetz.UUCP>
Date: Tue, 10-Jun-86 11:31:18 EDT
Article-I.D.: steinmet.782
Posted: Tue Jun 10 11:31:18 1986
Date-Received: Thu, 12-Jun-86 07:23:59 EDT
References: <540@gould9.UUCP> <2082@bmcg.UUCP>
Reply-To: davidsen@kbsvax.UUCP (Davidsen)
Organization: GE CRD, Schenectady, NY
Lines: 52
Xref: linus net.micro.pc:8206 net.unix:7401

In article <2082@bmcg.UUCP> shawn@bmcg.UUCP (Shawn Bosley) writes:
>In article <540@gould9.UUCP> joel@gould9.UUCP (Joel West) writes:
>>I'm still collating info for UNIX on a xxx86 machine (and would note
>>that I got a (postal) mailing from IBM in Austin about Xenix 2.0, based
>>solely on a previous posting.)
>>
>>I've narrowed myself to a 286-based system, probably a $3-$4k clone.
>>I definitely will be buying something that is still bundled, true
>>to the UNIX ideal.  I have two quick questions:
>>
>>1.  Which UNIX or XENIX take advantage of the protected mode?  (presumably 
>>    to prevent a misbehaving task from crashing the whole cpu).

Both IBM and SCO flavors of XENIX use protected mode. I believe that
the UNIX from Microport does also.

>>2.  Does the 286 chip still have that awful segmentation small model
>>    vs. large model crap?  Or, are there 286 instructions which make
>>    it possible to address > 64kb contiguously?  If so, does the
>>    C compiler for #1 support this?
>>

Fact of life with the 286. SCO XENIX C has a "huge model" which uses
long subscripts and treats memory as a flat addressing space. It has
worked for me on several projects, but I am *not* claiming it is bug
free. SCO XENIX supports ten virtual terminals so you can be doing
communications on one, switch to another to read mail, another to look
up a phone number of use a database, etc. The IBM version doesn't seem
to have this.

Comments on XENIX: the C compiler is *NOT* based on PCC. It has some
reasonable optimizing, generates code for many models, and has far
better error checking than PCC, but it won't compile some UNIX programs.

Suggestion: Microport UNIX for $350, having growing pains but uses real
PCC and uucp. This is a somewhat of taking a chance, but all of the
parts are SysV, rather than custom.

Why not buy a cheap 68k based system? Megadata is advertizing the hell
out of their $3200 system, and an ATT7300 with UNIX is about $5K (less
25% typically). I added a 32MB Tulin ($650) to mine and it runs great.
Lotsa good stuff around. Enjoy!
-- 
	-bill davidsen

  ihnp4!seismo!rochester!steinmetz!--\
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         sixhub ---------------------/        (davidsen@ge-crd.ARPA)

"Stupidity, like virtue, is its own reward"