Upgrading a Transwarp GS Board
By Andrew Hall
Copyright (c) 1991 Apple Users' Group, Sydney
Republished from Applecations, a publication of the Apple Users' Group, Sydney, Australia.
Prepared for the Western Design Center, Inc.
12 March 1990
DISCLAIMER: the following document contains suggestions from various people who have upgraded Transwarp GS boards. The author himself has not tried these! Follow these suggestions at your own risk. The author nor anyone else guarantees any of the procedures or tips below. The author and any of the companies mentioned within will not be held responsible for any costs or damages incurred as a result of attempting to upgrade a Transwarp GS board.
Western Design Center (WDC) created this document to help some special users of the Apple IIGS, journalists, consultants, engineers, and Apple Computer experiment with faster Apple IIGS systems and faster W65C816 microprocessors. New applications will be found when higher speed W65C816's exist.
Applied Engineering's Apple IIGS accelerator card, the Transwarp GS (TWGS), accelerates the IIGS to 7 MHZ. Even though AE does not yet sell a faster board or offer an upgrade, it is possible to increase the speed of a TWGS beyond 7 MHZ. Some users have had their boards running reliably as fast as 13 MHZ.
Yes, if you can't wait for an Applied Engineering upgrade, it is possible to upgrade the board yourself. Unfortunately, despite what you might have heard or read in InCider magazine, THE UPGRADE IS NOT TRIVIAL! This is one reason why AE does not yet offer faster boards.
By replacing the microprocessor and the oscillator on TWGS, you MAY be able to get a TWGS board up to 9 MHZ. To go any faster than 9 MHZ, you will have to do a lot of messy soldering to replace 3 static RAMs and change the power supply.
If you don't have any experience working with this sort of thing or if you are not a technical person, we highly recommend not attempting an upgrade like this. If you try the upgrade and you mess up your Transwarp board, you're on your own. WDC does not guarantee these engineering parts and does not offer further technical assistance for these upgrades. If you blow a W65C816, you're out US$95. If you wreck your TWGS board, you're out US$300.
Your TWGS board MUST have version 1.5 or greater to be able to run beyond 7 MHZ. Applied Engineering should provide a free upgrade ROM for you.
Below, then, are four upgrade steps. You need not carry out all the steps, but each step will allow your TWGS to run faster.
UPGRADE STEPS:
1. REPLACE THE CRYSTAL OSCILLATOR
The TWGS oscillator runs at 4 times the microprocessor speed (i.e. 28 MHZ for TWGS). You will therefore need to get an
oscillator 4 times faster than the speed at which you want the TWGS to run.
A "standard" TTL oscillator plugs into a standard 14-pin DIP socket. On TWGS, AE used a "1/2 TTL oscillator", which fits into a smaller 8-pin DIP socket. Unfortunately, this oscillator is not yet widely available in a variety of frequencies.
Supposedly, several Asian companies make the 1/2 TTL oscillator, but parts seem difficult to find. Your best bet is to get a standard TTL oscillator, which is bigger than the 1/2 TTL but has its four pins in the same orientation as the 1/2 TTL package, and solder leads onto the pins to fit into the oscillator socket on the TWGS. Look for the dot on top of the oscillator indicating Pin 1.
You can get standard TTL oscillators by calling local electronics suppliers. You might want to get at least two oscillators in different frequencies to play around with different speeds.
2. REPLACE THE MICROPROCESSOR
Because it requires no soldering, this is probably the easiest step. Western Design Center sells fast W65C816's in PLCC packages (the one used on TWGS) for about US$95 dollars.
WDC has two kinds of W65C816 parts that you can plug into a TWGS: "full-spec" parts and so-called "engineering parts". Engineering parts are a bit faster than the full-spec parts, but they have some current leakage problems that may make a system fail at lower clock frequencies (in the 100 KHZ range). An Apple IIGS running at 1 MHZ or faster should have no problem with this.
If you call WDC to order a fast W65C816, TELL THEM you are upgrading a Transwarp GS board. Get an engineering part if WDC has any; otherwise, get the fastest standard parts available.
Each engineering part is INDIVIDUALLY screened for high speeds. Some parts run as fast as 13 MHZ (you will need to check with WDC as to availability). For each engineering part sold, WDC supplies a "shmoo" plot.
The shmoo shows if the part passes its high speed test over a certain voltage range. The horizontal axis of the plot shows the PHI2 cycle time against the VDD input voltage on the vertical. An 'X' at a point indicates that the part passed the test at that voltage and cycle time. The operating frequency is calculated by: FREQ = 1/cycle time (denoted "TR" on the shmoo). Generally, increasing the voltage will increase the operating frequency.
The W65C816 PLCC chip is normally removed from its socket with a special tool. However, you can remove it with a stiff wire if you are careful. There are four holes on the PLCC socket, one on each corner. Carefully stick the wire into each hole and pry the chip out. Pry it out a corner at a time until it comes loose.
Note that the PLCC package is specially shaped or "keyed" so that you can't plug the chip in sideways.
3. REPLACE THE CACHE SRAMS ON THE TWGS
The removable "piggy-back" board on the TWGS contains 3 8Kx8 static RAMs (SRAMS) and an EPROM. Unfortunately the three RAM chips are soldered to the piggy-back board. You will have to de-solder the three chips from the board and replace them with 28-pin DIP sockets. Note that you may destroy the RAM chips that are already on the board. Remove the EPROM before you start soldering. Spend the extra dollar and purchase sockets for the RAMs. Solder in sockets, then plug in the new RAMs.
Most TWGS boards come with 45ns static RAMs. You will need (probably) 20 or 25ns RAMs to go any faster than about 9 MHZ. If you want to get into the 13 MHZ range, be sure to get 15ns RAMs.
Try local distributors, or look for ads in the back of computer magazines; many companies sell RAMs these days. You want an 8Kx8 Static RAM, 28-pin DIP (Widebody), plastic package. Low power RAMs (as opposed to standard power) are recommended.
The following companies manufacture fast 8Kx8 SRAMS: Toshiba, National, Integrated Device Technology (IDT), Cypress, and others. Prices may vary from US$12 up to about US$30, so check around if you can. The faster RAMs and the low power RAMs will cost more.
4. INCREASING THE TWGS POWER SUPPLY
WARNING: This step requires you to CUT wire traces on the TWGS PC Board. Cut the wrong trace, and you could wreck your board. Don't even *think* of attempting this step unless you really know what you're doing.
The TWGS normally uses the Apple +5 volt supply. However, you can get a little more speed out of the board by increasing the power supply voltage. You can use the +12 volt supply from TWGS edge card and an adjustable voltage regulator to produce a power supply voltage between 5-6 Volts. Make sure the voltage regulator is rated to at least 2 Amps; a 13 MHZ Transwarp card will draw a lot of current! Be careful with the power supply; if you have other cards that use the +12 volt supply, you could really be taxing
the supply. The Apple IIGS power supply is rated at 2.5 Amps at +12V.
How high should you adjust the voltage? If you purchased an engineering part from WDC, use the shmoo plot to determine what voltage will allow the part to run at the speed you're aiming for. It is not recommended that you raise the supply higher than about 5.8 volts.
WARNING: DO NOT RUN THE TWGS HIGHER THAN 6 VOLTS OR YOU WILL DESTROY IT!!!
You must disconnect the +5V supply in two places: near the edge card connector and on the DIP header cable (the little cable that plugs into the IIGS microprocessor socket). Cut the trace on the front of the TWGS PC board from pin 25 on the edge card (this is +5V). The trace is marked with a + on the TWGS. Also, cut the wire on the DIP header cable coming from pin 8 (VDD) on the microprocessor socket.
There is no easy way to describe which wire is connected to pin 8. Use an ohm meter to find out which wire is pin eight on the DIP header and cut that wire. You can also get the connectors to build a new cable. The IDC connector is a standard 40-pin connector. However, there are two kinds of 40-pin DIP headers. The one used on TWGS is the less common type with the pin rows reversed.
HOW FAST CAN TWGS GO?
You should be able to get 8 MHZ out of ANY TWGS board by carrying out steps one and two; if you can find the 1/2 TTL oscillator, you won't even need to pick up the soldering iron. Some TWGS boards could run at 9 MHZ by doing these steps (you will need to try it for yourself). If you think the speed increase from 7 MHZ to 8 or 9 MHZ is worth US$100, fine.
By carrying out the first three steps (replacing the RAMs as well as the CPU and oscillator), you should be able to get your TWGS up to 10 MHZ.
To get into the 13 MHZ range, you will need to raise the power supply as described in step four. As noted there, be sure you know what you're doing before you try this, or you could ruin your TWGS.
Remember that you must have TWGS firmware version 1.5 or greater to perform the upgrade.
IS IT RELIABLE?
The steps above are only part of the work involved in upgrading the TWGS. The rest involves testing your upgraded board.
Even if your newly upgraded TWGS works fine right after you turn on the power, it may not work flawlessly under all conditions. Let the board run for a few hours until it gets warm. Try "worst case" conditions (the way you would normally use your computer), THEN see how it works. Generally, raising the temperature of IC's reduces their performance. Note that microprocessors and memory chips all vary a bit in their performance; some TWGS's may work better than others.
Run the TWGS desk accessory self-tests (the speed switch test may fail; this might be OK). Run software that you normally use as part of the reliability test. If you have Appleworks GS, try running that. Several people have claimed that this will really prove whether a TWGS is reliable. Try running all the modules after the board gets warm.
Don't brush off this last important step. You wouldn't want to find out right in the middle of some important work that your TWGS bombs when it gets hot.
If you find that your upgraded TWGS is unreliable, you may need to try a slower oscillator or a faster microprocessor (or raising the supply voltage for those so daring).
IS IT WORTH THE EXTRA COST?
Users who upgrade their boards do so at their own risk. You may spend about US$150 just to try. If you really don't NEED the speed, wait for Applied Engineering to come out with an upgrade. In the meantime, try to appreciate how well your Apple IIGS performs at 7 MHZ.
If you are interested in purchasing a W65C816 microprocessor then contact Western Design Center and obtain an order and information form W65C816PL-ENG. Also ask about any updates to this document.
Western Design Center, Inc.
2166 East Brown Road
Mesa, Arizona 85203
602-962-4545
[Sub-editor's note: Two Series Software now have 32k Cache RAM upgrades for the Transwarp GS card at $175]

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