Re: Zip GS, 65816

[supertimer@aol.com (Supertimer)]

danaeckel@yahoo.com wrote:

>Hi,
>
>I have a Rom 3 Apple II GS with a 8mhz zip GS card installed. I would
>like to know where I can get a 20MHZ 65816 chip.
>
>Also, can I increase the cache on the Zip board?

Sure, you can do both.  For a 65C816 chip tested to work at 20Mhz,
you need to get it from a company called CMD (Creative Micro Devices).
However, these are really made by Western Design Center of Mesa
Arizona (you can find their web site by doing a web search for them).
WDC calls the chips "14Mhz" chips for the simple reason that they
only test them up to that speed.  CMD buys chips from WDC and
contracts an outside lab to test them up to 20Mhz.  Now, as I recall
from the CMD people, almost all the chips pass the 20Mhz test.
This means that the "14Mhz" chips are probably almost all really
20Mhz chips (meaning save the trouble and get the chips from WDC
rather than CMD).

Nonetheless, they only function at 20Mhz in a Commodore accelerator.
On the Zip GS or TransWarp GS, when you get up to around 15Mhz
or 16Mhz, the OTHER chips on the card become the limiting factor
(the cards were designed LONG before the 20Mhz 65C816 came into
being).

You could increase the cache on a Zip board by simply replacing
the RAM chips on them with higher density ones.  The accelerator
FAQ (which I believe was just posted) tells how to do this.  Note:
most Zip boards use .6 mil wide chips while most faster RAM chips
of the type are .3 mil wide, so you probably need to purchase
adapter sockets (about $7) or solder in new rows of socket pins.

Frankly, I've been less impressed with cache upgrades than with
CPU Mhz upgrades.  I'm sure when you see the effects of both, you'll
agree.  I recommend trying the CPU upgrade first if you were to
choose one.