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From: tim@cit-vax.Caltech.Edu (Timothy L. Kay)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Intel Microprocessors
Message-ID: <3613@cit-vax.Caltech.Edu>
Date: Thu, 13-Aug-87 04:35:17 EDT
Article-I.D.: cit-vax.3613
Posted: Thu Aug 13 04:35:17 1987
Date-Received: Sat, 15-Aug-87 07:28:14 EDT
References: <234@etn-rad.UUCP> <174200061@uxc.cso.uiuc.edu> <414@parcvax.Xerox.COM> <244@etn-rad.UUCP>
Reply-To: tim@cit-vax.UUCP (Timothy L. Kay)
Organization: California Institute of Technology
Lines: 33
Keywords: xt/370 at/370
Summary: list of other xt/370 problems

In article jru@etn-rad.UUCP (0000-John Unekis) writes:
>In article burton@parcvax.xerox.com.UUCP (Philip M. Burton) writes:
>>
>>IBM also used a slightly modified version of the 68000 to build a "370 on a
>>chip"  I recall that this was done about 1980, using two 68000's with
>>modified instruction sets.  I'm not sure if this ever made it to a product,
>...
>   Yes, it was announced as a product, the PC AT/370. It didn't live long 
>   though. It used 2 MC6800 chips with the instruction set completely redone
>   to be a clone of the 370 (they had to start with the 68K because of the

I have used an xt/370 for some work.  It not only suffers from terribly
poor performance, but it has other problems as well.  They ported VM, but
in the process they destroyed its capability to do multitasking.
Furthermore, they used an old version of VM, so lots of the more recent
functionality are missing.  They only support 4 megabytes of memory.
Also, the version I had only emulated a 3277 type terminal which is
horrible.  THEY EVEN EMULATED THE FACT THAT THE 3277 LOOSES INTERRUPTS.

It is true and impressive that the 370 instruction set was implemented
using re-microcoded 68000's.  What was not mentioned was that the
floating point was implemented using a re-microcoded 8087, which talked
to the 68000's!

The xt/370 and at/370 are typical examples of IBM trying to solve problems
by compatibility rather than innovation.  They made a mess.

>   system 9370 which they are trying to call the 'VAX-KILLER' Chuckle-chuckle-
>   snort-giggle.

I have heard that the 9370 is selling like hot-cakes.  It isn't simply a
compatible system.  It happens to be a very good one as far as
cost/performance.  It also runs Unix, and it has ASCII ports.