Newsgroups: comp.windows.ms
Path: utzoo!utgpu!watserv1!sunee!gpsteffl
From: gpsteffl@sunee.waterloo.edu (Glenn Patrick Steffler)
Subject: Re: vga speed
Message-ID: <1991Jan7.160127.25819@sunee.waterloo.edu>
Keywords: vga, graphics
Organization: Gerbils On Speed Inc.
References: <16972@ists.ists.ca>
Distribution: na
Date: Mon, 7 Jan 91 16:01:27 GMT
Lines: 54

In article <16972@ists.ists.ca> pasquale@sgl (Pasquale Leone) writes:
>   As the owner of an ATI VGA1024 card who is thinking of buying
>   a smart graphics card(8514, etc) I would like to know if
>   it is worth the money. What I mean is how much faster is
>   an 8514 going to be than my VGA. 10% ?  Twice as fast ? 10 times as fast?

Pasquale,

I have over two years experience in windows 3.0, and in this time I have
used VGA boards from several different manufacturers, used an 8514/a
PS/2, and tested a 34010 card.

Given the phenominal speed of the DOS demos for both the 8514/a and the
34010 card, I was *extremely* dissapointed with the lack of performance
realized in the windows environment.

Most applications "massage" output before going to the video driver in
order to make the update look smooth.  Unfortunately, this renders 
graphics co-processors almost useless, as this pre-processing step is
done entirely within the CPU memory by the main processor.  The only way
a fast video co-processor could help is if it could do the bit copy operation
from main memory to video memory faster than say a simple VGA card which
has no special hardware.

Unfortunately, the main PC bus is so damn slow it inhibits any quick transfer
of data from main memory to video memory.  The number of wait states to write
a single byte (be it one or two pixels) is almost 20!!  As opposed to 
mabe 1.2 on average for main CPU memory.

Therefore, from this information, and by the demos I have seen, I would
recommend you hold off on a graphics board purchase, and possibly 
add more memory to your system, or increase the processor speed.  Both
these will allow windows programs to work with internal bitmaps, and
keep more data around which would be discarded in a low memory situation.

>   Can anybody out there who has access to both a VGA equiped machine
>   and one with a graphics coprocessor board please tell how
>   much faster one is than the other.

I would say that the only speedup you would realize would be with the`
256 colour VGA drivers.  They are not optimized as yet, and in the next
few months 30-40% speedups will be available by upgrades from the 
manufacturers, as microsoft releases better DDK kits.

The internal bitmap drivers will be much faster in the next release for
the 256 case.  (rumour again...but founded on stuff I'va seen).

>pasquale@sgl.ists.ca

-- 
Co-Op Scum                            "Bo doesn't know software" - George Brett

"The galaxial hearth steams the sea as the sky blood red embrasses darkness"
-John Constantine (HellBlazer)                          Glenn Steffler