palarson@watdragon.waterloo.edu (Paul Larson) (02/28/88)
Why is it that some of the 020/881 add-on cards allow the SE to perform
faster than the Mac II? It seems to me that a machine built around these
two processors should be able to out-preform one which merely has the processors
added on as an afterthought. Is there some flaw in the Mac II architecture?
Johan Larson
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Posting from the | Secrecy is the keystone of all tyranny.
account of Paul Larson | - Heinlein
------------------------------------------------------------------------fry@huma1.HARVARD.EDU (David Fry) (02/29/88)
In article <5398@watdragon.waterloo.edu> palarson@watdragon.waterloo.edu (Paul Larson) writes: > >Why is it that some of the 020/881 add-on cards allow the SE to perform >faster than the Mac II? It seems to me that a machine built around these >two processors should be able to out-preform one which merely has the processors >added on as an afterthought. Is there some flaw in the Mac II architecture? The upgrade machines are generally (slightly) faster because they use high speed, more expensive, static RAM as opposed to dynamic RAM (slower but cheaper) in the Mac II. David Fry fry@huma1.harvard.EDU Department of Mathematics fry@harvma1.bitnet Harvard University ...!harvard!huma1!fry Cambridge, MA 02138
ephraim@think.COM (ephraim vishniac) (03/02/88)
In article <5398@watdragon.waterloo.edu> palarson@watdragon.waterloo.edu (Paul Larson) writes: >Why is it that some of the 020/881 add-on cards allow the SE to >perform faster than the Mac II? It seems to me that a machine built >around these two processors should be able to out-preform one which >merely has the processors added on as an afterthought. Is there some >flaw in the Mac II architecture? The Mac II is designed to allow use of 150nS memory chips. It uses one wait-state per memory access (if my own memory serves!). Some of the accelerator cards for the SE use faster memory chips and no wait-states during memory access. So, they're faster at the same system clock rate. The tradeoff is between cost and performance. From what I read in the trade press, I see that some of the accelerator boards use a relatively small, very high speed cache memory to avoid the need for a large amount of expensive RAM. It's simpler and cheaper to build a system with a uniform memory structure. Whether you consider this a flaw in the Mac II architecture depends on your thirst for speed and the depth of your pockets. Ephraim Vishniac ephraim@think.com Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142-1214 On two occasions I have been asked, "Pray, Mr. Babbage, if you put into the machine wrong figures, will the right answers come out?"
isle@eleazar.Dartmouth.EDU (Ken Hancock) (03/02/88)
In article <5398@watdragon.waterloo.edu> palarson@watdragon.waterloo.edu (Paul Larson) writes: > >Why is it that some of the 020/881 add-on cards allow the SE to perform >faster than the Mac II? It seems to me that a machine built around these >two processors should be able to out-preform one which merely has the processors >added on as an afterthought. Is there some flaw in the Mac II architecture? Not at all. It's the design of the NuBus architecture which allows the flexibility of expansion. There are in fact 020/881 boards that run faster than 16 MHz so they will ignore the 68000 processor. The Mac II, similarly, will be able to be upgraded to 030/882 boards and will subsequently be able to run faster as well. Ken -- Ken Hancock | UUCP: isle@eleazar.dartmouth.edu Personal Computing Ctr. Consultant | BITNET: isle@eleazar.dartmouth.edu __________________________________/ \____________________________________ DISCLAIMER: If people weren't so sue-happy, I wouldn't need one!
gillies@uiucdcsp.cs.uiuc.edu (03/02/88)
Also, color quickdraw may be slightly slower than normal quickdraw.
It is much more sophisticated than the original version of quickdraw.
I may be wrong -- I hear color quickdraw uses some 68020 instructions
for more performance.
Some benchmarks involve screen display, and a sloppy reviewer might
leave the Mac II in color mode, slowing it down.
Don Gillies {ihnp4!uiucdcs!gillies} U of Illinois
{gillies@p.cs.uiuc.edu}