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From: pho@vmsa.oac.uci.edu
Subject: Re: 16 MHz 64k Zip Benchmarks
Nntp-Posting-Host: vmsa.oac.uci.edu
Message-ID: <2C60EB21.15988@news.service.uci.edu>
Newsgroups: comp.sys.apple2
Organization: University of California, Irvine
Lines: 98
Date: 5 Aug 93 11:12:33 GMT

Posted for Long Hoang.


Frank,

Here are some more info that you might find useful for the TWGS/Zip FAQ.

NoiseTracker v1.0/1.1 reports 11.271 MHz for a 16 MHz 64k Zip GSX.  I believe
someone mentioned 10.33 MHz for a 15 MHz TWGS.  Correct me if I'm wrong.


 6. Where can I buy crystal oscillators?

        for Zip you need:
        1/2 TTL or full TTL?  Speak up Zip owners!

The Zip can use three types of crystals including the common 4-pin full TTL
crystal oscillator, 4-pin 1/2 TTL crystal oscillator (also used on TWGS) and
2-pin crystal (little metal canister about 1/4 the size of 1/2 TTL).  To be
able to use a 2-pin crystal, your Zip must have a resistor at R1 and capacitors
at C13 and C14.  I've found these three parts to be missing from current Zips.
No big loss since 2-pin crystals are less common and are only available up to a
certain frequency.  I have the values of those parts written down somewhere and
will post them when I find them.

For experimenting with different frequencies it makes it easier if you install
a socket for the crystal oscillator.  It's also a good idea to secure it down
with one of those zip tie bands.  Only 6 of the 14 pins are used (picture A).
The ground (GND) pins 1, 4 and 7 are connected together.  The power pins 11 and
14 are connected together.  Full TTL crystal oscillators use pins 1, 7, 8 and
14 (refer to picture B).  1/2 TTL crystal oscillators use the bottom four pins
(4, 7, 8 and 14; picture C).  Make sure it's oriented correctly with the corner
(usually with a dot printed next to it) at about 11 o'clock.


	WARNING*  The crystal oscillator will be damaged if installed incorrectly.


                                 _______
GND  1 o  \/  o 14  POWER     1 |o      \  14
NC     x      x     NC          |        |
NC     x      x     NC          |  FULL  |           ______
GND  4 o      o 11  POWER       |  TTL   |        4 |o     \  14
NC     x      x     NC          |        |          |  1/2  |
NC     x      x     NC          |        |          |  TTL  |
GND  7 o      o  8  CLOCK     7  \______/   8     7  \_____/   8

         (A)                       (B)                 (C)

x - no connection (NC)


 7. What speed of static cache RAMs do I need?

        for Zip you need:
        speak up Zip owners.

I've found Japanese and American static rams to work the best (20 ns in tag and
25 ns in data).  The Zip can use narrow (.3 mil) or wide (.6 mil) static rams.
It all depends on the sockets that are installed on your Zip.  With a little
modification you can make a Zip with wide sockets accept both wide and skinny
static rams.  Ground yourself then carefully pry out the static rams.  Look at
the socket and you will notice two or three horizontal bars holding both sides
of the socket together (picture D).  Carefully cut those out.  This will expose
a column of holes where you will solder in half of a socket.  Refer to picture
E, position skinny (.3 mil) static rams over the left and center columns and
wide static rams over outer most columns and making sure the notch on the
static ram is facing 12 o'clock.


	WARNING*  Plug the static rams in wrong and you will destroy them.



    CUT
    ___           ___________ Skinny (.3 mil)
   |   |         |   |
 ____ ____       _   _   _
|o __V__ o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|__o__|o|     |o| |o| |o|
|o _____ o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|  o  |o|     |o| |o| |o|
|o|__o__|o|     |o| |o| |o|
|o _____ o|     |o| |o| |o|

                 |_______|___ Wide (.6 mil)

    (D)             (E)


12. Is it true that Zip can only go about 12.5 mHz?

Only if you don't know how to make it run faster.  With a little bit of work it
can run up to 16 MHz just fine and possibly even faster.