From: beyonddeath <justhunt1234 AT home DOT com>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: hmm can someone help me with VESA
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Date: Sat, 01 Apr 2000 18:04:11 GMT
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

this works without 0x0 but not in my program if i make a program that
starts up into that mode then getch(); then closes works fine but in
mine it doesnt make the change...

On Sat, 01 Apr 2000 11:55:26 GMT, "AndrewJ" <luminous-is AT home DOT com>
wrote:

>Darn it, I went and replied this to an older message posted by you by accident.
>Here is the entire text cut 'n pasted. =)
>
>[snip]
>
>> union REGS regs;
>> regs.x.ax = 0x4F02; /* change display mode */
>> regs.x.bx = 117; /* three-digit mode number */
>> int86(0x10, &regs, &regs); /* Call the BIOS (int10) */
>> if(regs.h.al != 0x4F)
>> {
>> printf("VESA modes NOT supported!\n");
>> }
>
>[snip]
>
>Well, I see one problem right off the bat.  Mode numbers are generally given in
>hex, NOT decimal, so when your trying to set it to mode 117, you're giving it
>an invalid vesa mode (0x75, which isn't even a vesa mode).  Try setting it to
>mode 0x0117 instead and you should get proper results.
>
>Secondly, going with the assumption that this would be a complete program, you
>aren't following the recommended steps for use vesa.  Ideally you should be
>allocating a block of real-mode memory (dpmi functions will do this), getting
>the vbe information to check that vbe is actually installed (unless you only
>intend to use this on your system and you know you have vbe), going through the
>mode list pointer getting information about each mode until you find the one
>that corresponds to the mode you want, and *then* setting the mode.  In VBE 2+
>it was no longer required by the specification to continue using fixed mode
>numbers for various modes, so in theory mode 0x0117 might not even be
>1024x768x16bpp on your system (although I've yet to hear about a card that
>didn't retain all the old VBE 1.x mode numbers).
>
>Hope this helps,
>
>AndrewJ
>
>
>