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From: housen@ssc-vax (Kevin Housen)
Newsgroups: comp.sys.mac.hardware
Subject: Slowness of 8*24GC card
Summary: Whatsagoinonhere?
Message-ID: <3535@ssc-bee.ssc-vax.UUCP>
Date: 27 Nov 90 21:37:25 GMT
Sender: news@ssc-vax.UUCP
Reply-To: housen@ssc-vax.UUCP (Kevin Housen)
Organization: Boeing Aerospace & Electronics
Lines: 38


We recently installed an 8*24GC video card on an FX.  The spec sheets
imply that the card should speed up some graphics operations by a
factor of 5 to 30.  We have found that the card does speed up some
things.  However we have also found that the card actually degrades
performance in other cases.  I am wondering if anyone else has played
with the card and has had similar experiences.

An article in the Nov 13 MacWeek summarized some speed tests with
and without the GC card.  E.g. they found significant speed increases when
scrolling through a MS Word document.  We found comparable results in 
Word (factor of 1.3 speed increase in 1 bit mode, factor of 4 in 24 bit
mode).  However, when scrolling the same document in WriteNow 2.2,
we found that scrolling with the GC turned on was a factor of 3
slower than it was with the card off (that test was in 1 bit mode).
So Word and WriteNow showed opposite trends.

I wrote a quick ditty that does repeated CopyBits calls, drawing an
image at random locations on the screen.  We found that (in 8 bit mode)
the progam ran a factor of 2 slower when the GC was turned on
compared to when it was off.

I wrote another program which draws 16000 random lines on the
screen.  In that case, the card sped up the drawing by a factor of 2.

Does anyone have any idea whats going on here?  Right now I am of
the opinion that before buying one of these cards, you ought to test
it with the software you plan to use.

BTW, the tests mentioned above were done on an FX with 8 Meg,
an Apple Two Page monitor, System 6.05, no INITs (other than
the GC INIT).  The GC card has the extra DRAM installed.  I also
tested the card on a vanilla Mac II, with similar results.

Thanks heaps -

Kevin Housen
housen@ssc-vax