From: Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Virtual screen in ALLEGRO
Date: Tue, 4 Feb 1997 20:13:40 +0000
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Jan Safranek writes:
>I use allegro 2.11 with 640x480 graphics and
>I need 4 "pages" - I initialize graphics with
>set_gfx_mode(GFX_AUTODETECT, 640, 480, 640, 4*480)
>
>But if I display VIRTUAL_H and VIRTUAL_W, I get 1024 x 1024. This size of
>virtual screen support only 2 "pages" so I must always swap pages from/to
>memory and it slows down the program.

How much video RAM do these machines have? To get four pages, you'll
need at least 2 megs in the card.

But even if there is only 1 meg available, Allegro should refuse to set
the mode at all, rather than just giving you a 1024x1024 screen. And on
my machine, that's what it does. 

There's something wrong here, that needs fixing. If you could let me
know what sort of graphics card you have, and which driver and virtual
screen size are chosen when you run test.exe with GFX_AUTODETECT in
640x480, it would help a lot...

/*
 *  Shawn Hargreaves - shawn AT talula DOT demon DOT co DOT uk - http://www.talula.demon.co.uk/
 *  Ghoti: 'gh' as in 'enough', 'o' as in 'women', and 'ti' as in 'nation'.
 */