AW: mu[ot]

From: Kautzmann Gerd (
Date: Tue Apr 09 2002 - 13:50:55 CEST

> -----Ursprüngliche Nachricht-----
> Von: Garry thomas Tucker []
> Gesendet: Dienstag, 9. April 2002 12:08
> An:
> Betreff: mu[ot]
> just out of interest, why is it that running x
> with the svga server and afterstep on 800x600 is
> a lot smoother and quicker than 640x480 on vga16?

cause when you change one pixel in vga16 the prozessor
has to calculate the adress gets the byte from the graka
( reading from graka is slow ) fiddles out if high or
low byte has to be changed ( shifting bits is slow )
and write it back.

If the vga16 driver is a very simple one, that allways
uses a funktion like 'write pixel' to make his grafik
operations, without a copy in a fast ram, this driver
will be the slowest possible screen mode ever.

Thats why I like chunky screen modes. One byte per
pixel is usually faster than two pixels per byte.
( except some exotic grafik operations )

cu Gerd
> ----------------------
> Garry thomas Tucker
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