A faster Apple IIgs
by Chris Nelligan
Copyright (c) 1993 Apple Users' Group, Sydney
Republished from Applecations, a publication of the Apple Users' Group, Sydney, Australia.
When you purchase your Apple IIgs it is running at a predetermined speed. This speed was set by the designers at Apple Computer, a standard IIgs runs at 2.8 MHz. The original Apple II's ran at 1 MHz, Apple did release in the U.S.A a IIc that ran at 4 MHz using the Zip chip.
Why 2.8 MHz? I am not sure why 2.8 was chosen, many people have said that Apple did not want the IIgs to compete against Macintosh computers that were available at the time. More than likely the overall design of the computer played the major role in the final speed.
Many owners of the Apple IIgs have increased the speed of their machine by purchasing an Accelerator card. There are two accelerator cards available for the IIgs. The first is the Transwarp GS manufactured by Applied Engineering and the second is the Zip GS, manufactured by Zip Technology.
Applied Engineering have stopped really supporting the Apple II, Zip Technology however continue to support the Apple II. Hence all new guaranteed 'off the shelf' speed improvements are really only available via the Zip.
The Apple IIgs uses a processor chip called the 65C816 and was designed by the Western Design Centre. Recent hand-held game machines use the 65C816 processor, and a lot of pressure was placed on the chip industry to make a faster one. Sanyo ended up doing this, and redesigned the 65C816 so that it runs reliably at speeds faster than 14 MHz.
Only 14 MHz I hear you say, Mac's run at 20 MHz+ ! Yes this is true, the Mac uses a 680x0 processor made by Motorola. These processors handle 32 bit operations, the 65C816 only handles operations 16 bit wide. You know what, the more bits, the faster the processor you need. This is why comparing computers by the megahertz of their processor is not always a true indication of their speed differences.
Apple have released two Apple IIgs's, the original ROM 1 in 1986 and the ROM 3 in 1989. The ROM 3 was slightly redesigned and ran a bit smoother electronically, because of this, it is possible to accelerate the ROM 3 more than the ROM 1.
It is now possible to purchase from Zip, an accelerator for the ROM 1 that will make it run at 12 MHz, and at 14 MHz on the ROM 3! This is significantly faster than the original 2.8 MHz.
The Transwarp can still only be purchased at a speed of 7 MHz. It is possible to increase the speed of a standard Transwarp, however the 32k cache version is required.
How do I increase the speed of my Transwarp I hear you ask?
1. Buy from Western Design Centre a new 14 MHz processor, it will cost about AUS $190 to land it and put it through customs (depending on the dollar).
2. Purchase a new oscillator module from Clarke & Severn (Hornsby, NSW) for $27.
3. Fit these two new components on your Transwarp and hey presto a faster IIgs.
A ROM 1 can reliably be increased to a speed of 11.5 or 12 MHz on a Transwarp using a new oscillator with a speed of 48 MHz. A ROM 3 can be increased to at least 13.5 MHz using an oscillator with a speed of 54 MHz (The oscillator is a factor of 4 of the required running speed of the processor).
My Apple IIgs is now running reliably at 13.5 MHz after about 4 months of trying (I am waiting for a new oscillator to try for 14 MHz) . Since the Transwarp was designed to run at 7 MHz, it is pot luck at what the maximum speed your Transwarp will run at. I started at 12 MHz and have been buying new oscillator modules in 1/2 MHz increments until reaching my current speed.
As you have read, purchasing the Zip for faster speed is a lot easier than increasing the speed of your Transwarp. If you would like assistance in performing the upgrade on your Transwarp I can be contacted by mail at P.O. Box 271, Turrumurra NSW 2074.

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