Path: utzoo!attcan!uunet!bcstec!iftccu!bressler
From: bressler@iftccu.ca.boeing.com (Rick Bressler)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: 640 * 480 256 color mode errors Trident 16-bit SuperVGA Card
Message-ID: <5400001@iftccu.ca.boeing.com>
Date: 25 Jan 91 01:05:49 GMT
References: <366@rc6.urc.tue.nl>
Organization: Boeing Commercial Airplane Group
Lines: 14

I had a similar problem.  Turned out that the default drivers were using 
non-interlaced modes and my monitor while a multi-sync would only handle those
frequencies in an interlaced mode.  I recall patching the driver sets I used
with debug.  Problem solved!

I don't have the manual here at the moment, but near as I can recall
these modes are documented in the manual.  I was wondering at first why they 
had modes that appeared to be identical.  More digging identified the lower
numbered codes ~ 40 - 49 being the non interlaced and 50 - 59 being the 
interlaced modes.  If there is enough interest, I might be able to 
retrace my steps (pardon the pun) and post a general guideline for 
finding and patching the problem.

Rick