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Mail Archives: djgpp/2003/01/12/16:00:09

From: "Joel_S" <jbs30000 DOT news DOT invalid AT web2news DOT net>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: VGA DAC programming
Date: Sun, 12 Jan 2003 21:54:58 +0100
Organization: Web2news.com
Message-ID: <10943N098@web2news.com>
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> Joel_S wrote:
>>
>> I just ran into a problem that I've never had before
>> trying to alter the
>> palettes in screen mode 0x12.  I can do this just fine using a VBDOS
>> compiler (QuickBasic compatible) but using DJGPP, or even
>> the real mode
>> Turbo C++ 3.0 not all of the colors from 0 to 8 can be
>> changed, and none
>> of the colors from 9 to 15 can be changed at all.
>> Here's a simple program that's supposed to
>> 1) Switch to VGA mode 0x12
>> 2) Change the color 12 to puple.
>> 3) Draw a line using the color 12.
> [snip code]
>
> I also tried in Win98SE, with the same effect (ie. red, not purple).
> Using mode 0x13 does change color, but that's not what you want. The
> video function to change the DAC also does not work (0x1010). Would
> it be possible to use color 13, which is purple (technically magenta)
> by default?
>
> Jason.
Well, since I'm writting routines for screen mode 0x12 being able to
change the palettes of the 16 colors is necessary for properly diplaying
a bitmap file.  But I'm not to worried, the built in SCREEN commands in
the MS QuickBasic through VBDOS not only can switch the screen to mode
0x12, but you can also change any colors palettes afterwards, so I'll
just study the vga regiesters and so on to see if I can find out the
difference between using SCREEN, and having the BIOS switch screen
modes.
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