My query to comp.sys.mac.hardware about cache cards broughtsome useful responses, and even more responses asking me to share
what I found out. I've now installed a Quicksilver IIsi. It consists
of a 20 MHz 68882, a cache consisting of 32kb of 25ns static ram, and a PDS
slot extender that would allow me to install an additional card
should I think of one I want. The price was $310 for overnight delivery
from MacConnection. Installation was trivial and took about 2 minutes
with no tools.
Subjectively I've observed major improvements in programs such as
MacDraw Pro, Freehand, and Theorist, although most of this is due to
the 68882 FPU. Based on the results of tests using Speedometer 3.05
(shareware available by anonymous ftp from info-mac at
sumex-aim.stanford.edu), the FPU yields an overall math speedup
(under a battery of 13 tests) of about a factor of 2, with things
like Whetstones going up by a factor of 6. The additional improvement
due to the cache is about 12% for the math battery, 3-4% for the "CPU"
test, 5-7% in 1-,2-, and 4-bit graphics, and 26% in 8-bit graphics,
where the Cache lives up to the claims of the improvement it yields in
scrolling. (Russell Donnan sent me a report of his own experiments
with a cache, and got a similar 23% speedup for a test involving
repeated string copies.)
In summary, with the Quicksilver my IIsi is now roughly 2.3 times
faster than an SE/30 (according to Speedometer) on math, and 1.55
times faster overall. This is under System 7.0 for me and (I think
7.0.1 for the SE/30). So the card was definitely worth the price,
although the jury is still out on whether I really needed the
cache. One piece of advice I received from several quarters
was not to bother with more than 32kb of cache as the residual
improvement obtainable by doubling or quadrupling that would
be only 1 or 2%. I also was advised by BMUG to get a card with
a good warrantee. (This comes with a 5-year warrantee and a Steve
Wozniak endorsement on the package.)
David Johnson
d...@research.att.com
