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From: msc@qubix.UUCP (Mark Callow)
Newsgroups: net.micro
Subject: Re: 80186 in a TRS80 - (nf)
Message-ID: <695@qubix.UUCP>
Date: Mon, 12-Dec-83 14:39:49 EST
Article-I.D.: qubix.695
Posted: Mon Dec 12 14:39:49 1983
Date-Received: Wed, 14-Dec-83 01:32:58 EST
References: <4321@uiucdcs.UUCP> <824@vax2.fluke.UUCP>
Organization: Qubix Graphic Systems, Saratoga, CA
Lines: 30

>	The problem with a 186 in the TRS 2000 is that it will not be IBM
>	compatible.  MS-DOS is rumored to use opcodes (or more properly
>	interrupts) that Intel reserved for future expansion and then used
>	in the 186.
>	
>	Many people believe this is why the IBM Peanut did not use the 188,
>	which would have made sense from a hardware or cost sense.
>	
----
Let's at least get the facts straight.  IBM used some Intel reserved interrupt
vectors for some of the ROM entry points on the PC.  Intel used some of these
same interrupt vectors on the 80188 and 80186 for vectors for some of the
features they added to these chips.

This problem is indeed the reason why PCjr uses the 8088.  BUT MS-DOS (and
even PC-DOS) are not affected so Tandy should have no problem meeting their
claimed level of compatibility.

Sources:

1)	Two articles here in net.micro, including one by someone
	(I've forgotten who) from Microsoft, explaining the problem in great
	detail.

2)	An article in EE Times when the PCjr was launched.  Mind you this
	article did gloss over the problem and imply that Intel was at fault.
-- 
From the Tardis of Mark Callow
msc@qubix.UUCP,  decwrl!qubix!msc@Berkeley.ARPA
...{decvax,ucbvax,ihnp4}!decwrl!qubix!msc, ...{ittvax,amd70}!qubix!msc