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From: toepfer@du9ds3.uni-duisburg.de (HaJo Toepfer)
Newsgroups: comp.sys.ibm.pc.hardware
Subject: Re: 640 * 480 256 color mode errors Trident 16-bit SuperVGA Card
Message-ID: <toepfer.664632858@du9ds3>
Date: 23 Jan 91 12:14:18 GMT
References: <366@rc6.urc.tue.nl>
Sender: @unidui.uni-duisburg.de
Organization: Rechenzentrum Uni-Duisburg
Lines: 15


I think the programs you tested try to to access the video ram directly.
In 640x480 mode with 256 colors those programs have to do bank switching
on the VGA card. Unfortunately bank switching on TVGA goes a quite unusual
way. As an owner of a TVGA too I tried to inspect the VGA-bios but found
nothing else than garbage. If you wnat to check out the general working of this
mode you should trie to access it via INT 10.

Bye the way: Any one out there who knows about accessing extended TVGA modes,
please post. Playing with FractInt I found out that even such good programmers
are not able to handle TVGA 's in the right manner.

Thanks a lot

	Hansjoerg Toepfer