Message-ID: <36CF686C.7365@teleline.es>
Date: Sun, 21 Feb 1999 02:59:08 +0100
From: Mariano Alvarez Fernández <malfer AT teleline DOT es>
Organization: teleline.es
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To: "StefanViljoen,6599" <rylan AT intekom DOT co DOT za>
CC: djgpp AT delorie DOT com
Subject: Re: GRX question
References: <19990219213654 DOT AAG23095 AT jackal DOT intekom DOT com DOT intekom DOT co DOT za@default>
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Reply-To: djgpp AT delorie DOT com

StefanViljoen,6599 wrote:
> 
> > 1- My video car is a S3 Trio 64, and using de S3 or the VESA 
> > driver I
> > can't start the 800*600 16 colors mode (even with modetest program).
> > No problem in other modes like 800*600 256 colors.
> 
> I have EXACTLY the same card - but I do not use GRX. Rather I use 
> Allegro, which supports this card natively up to its 16bit resolution. 
> My S3 has 1 meg of ram and works well with Allegro. Why not try 
> allegro instead of GRX?

I will try some day, but I'm confortable whith GRX because it's like
BGI. To answer other posts, I wrote 16 colors, no 16 bit colors. When I
start 800*600 16 colors mode I obtain only 640*480 16 colors.

> >   2- I have noticed the 16 colors modes are very slow, however the 
> > 256 colors modes are really fast. Are there any reason?
> 
> There is a very good reason - 16bit color uses more memory. In the 256
> color mode, you have one byte corresponding to one pixel - thus to 
> show 100
> pixels you use exactly 100 bytes. In 16bit color modes you have two
> or more
> bytes corresponding to one pixel. Thus, to show 100 pixels you
> need 200
> bytes. Get the idea? To use 16bit modes you have to write twice
> the number
> of bytes into video RAM - this is why it takes longer.
> 

No, i wanted to mean 16 colors, no 16 bit colors. 16 color GRX modes are
slowly than bios. I like this mode because it's more compatible.

Thanks anyway, M.Alvarez