03.015 How do I experiment with different oscillator frequencies?
Description
This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
03.015 How do I experiment with different oscillator frequencies?
Most of the following is from a piece on ZipGS upgrading by Long. It is
also a useful guide for TranswarpGS owners.
The ZipGS can use three types of crystal oscillators: the common 4-pin
"full size" oscillator module (about the size of a 14-pin TTL IC), a 4-pin
"half size" oscillator module (also used on TWGS), or an on-card circuit with a
separate crystal (little 2-pin metal canister). To be able to use a separate
crystal, your ZipGS must have a resistor at R1 and capacitors at C13 and C14.
These three parts are often omitted from Zips which use an oscillator module.
If your accelerator does not have a socket for the oscillator module, you
should probably install one (14-pin for ZipGS; 8-pin for TranswarpGS).
Experimenting with different frequencies will be much easier. (If your ZipGS
has eyelets for a 16-pin socket*, leave the top two pins open.)
On ZipGS boards, only 6 of the 14 socket pins are connected (picture A).
The Ground (GND) pins 1, 4, and 7 are connected together. The Power pins 11 and
14 are connected together; and, pin 8 is the module Output. Full size
oscillator modules use pins 1, 7, 8 and 14 (refer to picture B). Half-size
oscillator modules use the bottom four pins (4, 7, 8 and 11; picture C).
TranswarpGS uses an 8-pin socket intended for holding a half size
oscillator module (picture D).
Make sure the module is oriented with the marked end (usually having a
dot, squared corner, and/or notch) facing upward. Make sure the module is
oriented with the marked end (usually having a dot and/or notch) facing upward.
The lower two pins of the module should be in the lowest two pins of the
socket.
WARNING: The oscillator may be damaged if installed incorrectly.
ZipGS
* x x * _______
GND 1 o o 14 POWER 1 |o \ 14
NC x x NC | |
NC x x NC | FULL | ______
GND 4 o o 11 POWER | SIZE | 1 |o \ 8
NC x x NC | | | HALF |
NC x x NC | | | SIZE |
GND 7 o o 8 OUTPUT 7 \______/ 8 4 \_____/ 5
(A) (B) (C)
TranswarpGS
______
GND 1 o o 8 POWER 1 |o \ 8
NC 2 x x 7 NC | HALF |
NC 3 x x 6 NC | SIZE |
GND 4 o o 5 OUTPUT 4 \_____/ 5
x - no connection (NC)
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