Message-Id: <m10CS3l-000S62C@inti.gov.ar>
Comments: Authenticated sender is <salvador AT natacha DOT inti DOT gov DOT ar>
From: "Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
Organization: INTI
To: Shawn Hargreaves <ShawnH AT Probe DOT co DOT uk>, djgpp AT delorie DOT com
Date: Mon, 15 Feb 1999 14:47:05 +0000
MIME-Version: 1.0
Content-type: text/plain; charset=US-ASCII
Content-transfer-encoding: 7BIT
Subject: RE: Line frame buffer speed problem
In-reply-to: <8D53104ECD0CD211AF4000A0C9D60AE3538114@probe-2.acclaim-euro.net>
X-mailer: Pegasus Mail for Windows (v2.54)
Reply-To: djgpp AT delorie DOT com

Shawn Hargreaves <ShawnH AT Probe DOT co DOT uk> wrote:

> > Salvador Eduardo Tropea writes:
> >> That is _really_ weird.
> > >> totally different VESA driver...
> >
> > I saw this before in a TGUI9440 board. The Ivan Baldo board+motherboard 
> > combination makes the LFB slower than the banked mode. Looks like the
> problem 
> > is above/below 1Mb.
> 
> Well, I just learned something new! I've seen plenty of cards where 
> it is the other way around (writing to the linear buffer enables a 
> faster bus transfer mode, and avoids the card having to bother about 
> emulating the VGA write mode registers), but I can't think of any 
> reason why the LFB would be slower.
> 
> I don't suppose this could be something really stupid like Windows 
> trying to virtualise the framebuffer?

It was the first thing I thinked when Ivan told me that LFB worked slow. In 
fact I supposed that SciTech driver was virtualizing the memory to emulate 
the LFB and say "we support LFB for it too" ;-). But when Ivan used my own 
VBE/AF code ander plain DOS and using really low level things I saw the 
problem was something about hardware. I think the problem is related to the 
chipset. An interesting thing as that the TGUI board works faster (in VGA) 
than in my machine. So this chipset makes the normal access faster than my 
chipset. I tried changing the BUS clock of my machine but I didn't help.

SET 
------------------------------------ 0 --------------------------------
Visit my home page: http://welcome.to/SetSoft
or
http://www.geocities.com/SiliconValley/Vista/6552/
Salvador Eduardo Tropea (SET). (Electronics Engineer)
Alternative e-mail: set-soft AT usa DOT net set AT computer DOT org
ICQ: 2951574
Address: Curapaligue 2124, Caseros, 3 de Febrero
Buenos Aires, (1678), ARGENTINA
TE: +(541) 759 0013