From: Ludvig Larsson <ludvig AT club-internet DOT fr>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: GRX question
Date: Tue, 23 Feb 1999 02:44:26 +0100
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To: djgpp AT delorie DOT com
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Mariano Alvarez Fernández wrote:
> 
> Hi,
[snip]
>   2- I have noticed the 16 colors modes are very slow, however the 256
> colors modes are really fast. Are there any reason?
> 

8-bit colormodes are very easy to access, you just put the
apropriate 8-bit variable in the right place:)

4-bit colors are different, you have to share every char(8 bit, the
smallest variable you can use easily) so, writing
to one pixel on screen means that you have to look up the char
and then modify either the 4 lowest bits or the 4 highest bits
and then put everything back in the videomemory.
You can offcourse have a buffer in memory repressenting the
screen to avoud reading the slow videomemory, but even
with that, it will be slower.

HTH

Ludvig Larsson