From: Shawn Hargreaves <Shawn AT talula DOT demon DOT co DOT uk>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Vesa 1.0 Video Detection
Date: Sun, 19 Jan 1997 11:39:38 +0000
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Message-ID: <DerjQBA6fg4yEwQt@talula.demon.co.uk>
References: <5bm7mi$8ti AT dfw-ixnews9 DOT ix DOT netcom DOT com>
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To: djgpp AT delorie DOT com
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Takahiro Horie writes:
>Q. Currently I am using DJGPP and Allegro. I am asking for a routine
>   that simply checks to see if Vesa 1.0 Standard 640x480 256 colors
>   is available on the machine it is being run on- and if not, to
>   exit and display that error. Any one with an answer?

If you are happy just using Allegro functions, try:

    if (set_gfx_mode(GFX_VESA1, 640, 480, 0, 0) != 0) {
        printf("VESA mode not available\n");
        exit(1);
    }

If you want to use the VESA functions directly, you should first call
the VESA detection function (int 0x10, ax=0x4F00) to query if a VESA
driver is present, and then the get-mode-info function (int 0x10,
ax=4F01), to query if mode 0x101 is available. Get a copy of the VESA
spec from x2ftp, and have a look at the vesa.c sources in Allegro...

/*
 *  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'.
 */