Re: Need help with Zip

[pubpc1@library.ucla.edu]

JB wrote:
> 
> Can anyone give me an idea as to why my Zip (version 1.02) will crash my
> system when I have the dip switches set to recognize 32 or 64k cache?
> When I have it set to only recognize 16 it works just fine.
> 
> When it crashes it drops out of the GS/OS into some garbled text on my screen.
> 
> Any help is appreciated.
> 
> thanks!

Hmm...JB, it sounds like my Zip GS at 13.75MHz.  I have 64K
of cache installed, but I have to leave it set at 16K to make
it stable.  It depends on your 65C816 chip, the speed of the
SRAMs, and your particular GS.

Did you install a new 14MHz 65C816 from Alltech or WDC?  This
is needed to go above 10MHz.  You might be able to get the
older chip to go to about 10MHz with just an oscillator swap,
but this may require lowering cache size setting, as you've
discovered.  Next, what is the speed of your SRAMs?  If they
are 70ns in all four sockets labelled HM62256LP-70 or similar,
you should be able to set 64K.  If there are two of these
chips, you can only set 32K.

If you have 70ns chips in DATA, but 15ns in TAG, then your
Zip should be able to break 10MHz to the higher speeds.  Now
if your particular card and computer is less stable than
average, you might need faster parts just to get to a lower
MHz.  Another means of stabilization is to lower the cache
size setting, which is what you did.

Point your web browser to:

http://ground.isca.uiowa.edu/apple2/apple16/Hypermedia/Hypercard/

and download ZipUpgrade.SHK or ZipUpgrade.BSQ if you need
7-bit transfers.  This is my illustrated guide to upgrading
the Zip GS, a HyperCard IIGS stack.  Try installing the SRAMs
and high speed 65C816 from the sources listed and see if your
problem goes away.  The instructions were designed to give
you a 12.5MHz to 15MHz Zip, but if your card/computer is less
stable than normal, the higher speed parts can help you get
your 10MHz Zip to use all 64K of cache.

-Scott G.