Re: Zip GS?

[nathan@cco.caltech.edu (Nathan Mates)]

In article <area51-2104961651380001@pool057.max6.los-angeles.ca.dynip.alter.net>,
Adam Rumack <area51@earthlink.net> wrote:
>I've got a question...  What is the difference between a Zip GS and a
>regular IIgs?  I know the Zip GS is faster, but isn't is just a chip that
>goes on a IIgs, or is a whole different system?

   A Zip GS is a card that plugs into one (1-4, pretty much) of the
slots in the GS, as well as the processor socket on the IIGS. On the
Zip GS card is a set of cache ram slots (holding 8,16,32 or 64K of
cache), an ASIC for controlling the cache and interfacing with the
rest of the system, a few other 74xx chips, an accelerated 65816, and
an oscillator to drive that 65816. 

   Base Zip GS boards came with 65816 processors from 7-10Mhz; the
company may also have sold 14Mhz models for a little bit. By swapping
the oscillator and 65816, the end user could manually upgrade the
board to whatever speed they could.

   Programs that could run entirely out of the cache could run at the
full speed of the on-Zip 65816, but any accesses to non-cache memory
would go at either 2.5Mhz or 1Mhz depending on whether it was going to
fast or slow ram. The system bus is probably the biggest slowdown to
accelerate GSs.

Nathan Mates



-- 
<*> Nathan Mates http://www.ugcs.caltech.edu/~nathan/      <*>
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