From: pb@excelsior.xs4all.nl.REMOVE-THIS (Marc van den Dikkenberg)
Subject: Re: VESA video modes
 
On Mon, 23 Mar 1998 22:21:43 -0500, Robert Severn 
wrote:
 
>To set a VESA video mode, you have to set AX = &H4F02 and then put the
>video mode (&H111, &H114...) in BX.  Then do the INT &H10.  As far as
>actually doing anything in these modes, I know how to set pixels in the
>256 colour modes (that's easy, just write bytes to the video buffer) but
>as for the high colour modes I don't know how the pixels are stored.  So
>if anyone does, let me know.
 
I've been playing around with the hi-color modes for a little while now,
and did figure out that part. Hope this helps:
 
In a 16-bit mode, you have to poke two bytes for one pixel.
the first 5 bits are the red value, then 6 bits for green, and 5 bits for
red again.
 
&B RRRRRGGG
&B GGGBBBBB
 
In a 16-million color mode, you have a byte for each of the colors.
However, there seems to be a fourth byte of which I havne't found the
use yet. Probably just stuffing:
 
&B RRRRRRRR
&B GGGGGGGG
&B BBBBBBBBB
&B ??????????
 
So you poke 4 bytes for each pixel.
 
 
--
Marc van den Dikkenberg
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