03.023 How can I upgrade TWGS speed?
Description
This article is from the Apple II Csa2 FAQ, by Jeff Hurlburt with numerous contributions by others.
03.023 How can I upgrade TWGS speed?
The process is very similar to that described earlier for the ZipGS. That
is, you swap in a new 14MHz 65C816, a higher speed oscillator module, and,
possibly, faster 32k x 8 SRAM chips. As mentioned in Q&A 020, you should not
have to upgrade to faster GAL chips. Users with the newer GAL 3E in place may
actually need to swap in an older GAL 3A.
According to a 1992 Appleworks Forum article by John Link, you can get to
12.5MHz with an older 10MHz 65C816, a 50MHz oscillator, and 35ns SRAM without
upgrading to the faster GAL chips.
As with ZipGS, TransWarpGS speed = Osc Speed divided by 4. One difference
is that the TransWarpGS oscillator module is of the "half-size" kind. Another
is that, if RAM is upgraded, the usual practice is for all three to have the
same speed rating. If you do the SHH cache upgrade, there should be no need to
worry about replacing SRAM.
TransWarpGS boards vary just as do ZipGS boards. Some can be pushed to
higher speeds than others. If you decide to do a speed upgrade, get two or
three oscillators to allow for some experimentation.
For a step-by-step guide, download Scott G's TWGSupgrade.SHK. HyperCard
stack at ftp://ground.ecn.uiowa.edu/apple2/apple16/Hypermedia/Hypercard/ .
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By: Wayne Stewart
I have a TransWarpGS with rev A GALs and a rev 1.5 ROM. It came as 7mhz
with an 8k cache. It was pretty unstable when I recieved it, so I put in a
spare 14mhz 65c816 I had which stabilized it. Since I had a lot of rectangular
oscillators from my ZipGS upgrade experimenting, I made up an adaptor so I
could use them in the TransWarp. With those two changes it's running at 14mhz.
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By: Andrew Roughan
It's time (June 2003) for an update on this article. I have recently
purchased some more oscillators from Clarke & Severn Electronics. They can now
provide custom programmed oscillators in 1/2 TTL packages for AU$6.98 each.
I am currently running my ROM 3 system at 14Mhz. I have a Transwarp GS
with ROM 1.8S and the 32k cache from Applied Engineering (35ns SRAMs). The GAL
versions are TWGS1A1, TWGS2B1, TWGS3B1, TWGS4B1, TWGS5A1, TWGS6A1, TWGS7A1,
TWGS8A1. I have the 14Mhz 65816 available from WDC. I have not purchased faster
SRAMs or modified the power supply.
By: Rubywand
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