From: Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: VESA DoubleBuffer flicker and SetGetDisplayStart func 0x07h
Date: Sun, 2 Mar 1997 19:34:48 +0000
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To: djgpp AT delorie DOT com
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>I changed my code. Now I don't wait for VR in the set CRT
>Start Address, but I do an explicit wait for VR *after*.
>
>Everything is now rock-solid.

Weird! Are you by any chance running under win95? :-) That can sometimes
do bad things to retrace detection, by interrupting your program in the
wrong places. Eg. the VESA driver waits for retrace, retrace occurs,
VESA driver is just about to set the hardware registers when Windows
preempts it, so the display start doesn't actually get altered until
slightly _after_ the retrace, causing the flicker. 

That wouldn't make any sense if you are running in DOS, though...

/*
 *  Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
 *  Beauty is a French phonetic corruption of a short cloth neck ornament.
 */