[no subject]

Another source for oscillators is Digi-Key (800-344-4539).

 
Fast Cache RAM

You can get 64K's of fast cache from JDR Microdevices.
 
       Get 4 Static Cache RAM chips,
       Part #: HM62256LP-70
       Price: $4.69 per chip (you need 4 of these for 64K)
 
Note:  The speed of these SRAMs will be sufficient to around 10MHz.
       The advantage of these particular chips are that they are
       available cheap and in the wide 600 mil package that the Zip
       sockets require.
 
       For 15MHz operation, even faster SRAMs may be required.
       Unfortunately, they are mostly available only in the skinny
       300 mil packages.  To use them, half sockets must be
       soldered into the Zip. They are also more expensive.

       Also consider that the performance advantage going from 10MHz
       to 15MHz is far less dramatic than from 7MHz to 10MHz.
       Factor in the risk of seriously damaging the Zip during
       soldering.
 
       Conclusion: the 10MHz operation is safer, requires no
       permanent modification of the Zip, and the chips of the
       right size are available and costs a lot less.
 

Fast CPU

You can get a 14MHz fast CPU from:
        The Western Design Center  (http://www.wdesignc.com)
        2166 E. Brown Road         (email: information@wdesignc.com)
        Mesa, AZ 85213
 
        Part #: W65C816SPL-14 (for Zip GS or Transwarp GS
            accelerator cards for the Apple IIgs computer)
        Price: $19.80 + $4.00 shipping & handling
 
        (Western Design Center requires payment by Money Order)
 

Once you get the cache chips and the CPU, remove the 4 (or 2) old cache
chips and plug in the 4 new ones, making sure the orientation of the new
chips is the same as the old ones were (you've just replaced slow 32K of
cache with fast 64K cache).

Remove the CPU chip and plug in the new CPU.  Finally, experiment with
different oscillators, replacing the original, and find the fastest one
that works. DIP switch settings have to be changed when changing cache
size. There are two banks of DIP switches on the Zip card. Switches 7
and 8 on DIP bank 1 determine the cache size. Bank 1 is the bank of DIP
switches nearer the top of the card. The settings are as follows.

 
size            switch 7        switch 8
------------------------------------------
8K              on              on
16K             on              off
32K             off             on
64K             off             off
 
 
With a faster cache and 14MHz CPU, you may be able to go above 10MHz by
plugging in a 48MHz oscillator (for 12MHz Zip), or 64MHz oscillator (for
14MHz).
 
Even if you need a new cache and CPU in addition to a new oscillator,
you can still upgrade a 7/32 to a 10/64 and beyond for around $40. If
you are satisfied with 10MHz and are lucky and don't need the new cache
and CPU, then you'd get a 10/32 upgrade for the price of a $1.39
oscillator!

Good Luck!

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