From: T DOT Harte AT btinternet DOT com (Thomas Harte)
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Allegro problem
Date: Tue, 03 Jun 1997 00:07:05 GMT
Organization: BT Internet 
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On Sun, 1 Jun 1997 13:55:34 GMT, Fernando Salas
<fsalas AT impsat1 DOT com DOT ar> wrote:

>I 'm experimenting some problems with allegro 2.2:
>
>It's pretty simple, when I run the demo in 640x480 page flipping, the
>lower half of the screen appears twice . So you never see the upper half
>of the screen.
>Then I tried with UniVBE 5.3 , that fixes that problem but some
>filckering appears even with dirty rectangles technique. It seems like
>UniVBE and vsync() aren't too happy of been together.

	I had this exact same problem. However, it was on a four year
old 486 with an Oak Oti-67 graphics card, so I put it down to that
card & compatibility problems - especially as it all seems fine on my
S3 Virge not yet year old Pentium (the Virge is pin compatible with
the Trio 64 I believe).

	Sometimes however, the full screen would appear squashed to
half size repeated twice, depending on which applications I had run
first (largely Win 3.1 being the biggest factor). So really I tink
this is entirely down to the card manufacturer, and their
implementation of the VESA standard.

		-Thomas