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From: bert@helix.nih.gov (Bert Tyler)
Newsgroups: comp.windows.ms
Subject: IBM's XGA and non-386 PCs
Message-ID: <868@nih-csl.nih.gov>
Date: 28 Jan 91 22:06:01 GMT
Sender: news@nih-csl.nih.gov
Organization: National Institutes of Health, Bethesda
Lines: 19

>    I've heard that the XGA adapter requires a 386SX or better
>    machine. Any idea why ? 
  
It is my understanding (from Jake Richter, who wrote the AUTOCAD
drivers that come with that adapter, and who is writing a book on
programming the XGA) that the Power On Self Test (POST) software for
the XGA adapter that is executed when you power up your PS/2 uses
386-specific instructions, and for that reason you need a 386SX or
better.  The POST software was written by IBM.

It is quite possible that the Windows and OS/2 drivers supplied by IBM
for the XGA adapter also include 386-specific instructions.
 
The adapter itself does not appear to require any particular chipset -
Jake wasn't aware of the POST restriction when he wrote the Autocad
driver, so *he* didn't use any 386-specific instructions.  Also, I've
written code for MS-DOS that throws my XGA into each of its extended
modes and reads/writes pixels to the screen in each of those modes - all
using the ancient 8088 instruction set.