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Re: Technical Information for GS Accelerators
In article <7961e1f9.0305130903.211352f3@posting.google.com>, vector
<isbat1@yahoo.com> wrote:
> Hrm. Where can I find nicely detailed technical data about the
> Transwarp GS and/or Zip GS, up to and including schematics? Is there
> a source for that sort of thing? I'd also appreciate information on
> the general design of third-party hardware cpu accelerators, even if
> not Apple II specific. I'm sort of doing a research project.
Here is another nice FAQ specifically for the TransWarp GS accelerator,
again mostly related to overclocking the accelerator, but also
providing other technical information on the card. As far as
schematics, I haven't a clue where to look, but I wish you LOTS of luck
finding them.
Tidings of comfort and joy,
TK
-=-
U U PPPP GG RRR AA DDD IIIII N N GG
U U P P G R R A A D D I NN N G
U U PPPP GGG RRR AAAA D D I N N N GGG
U U P G G R R A A D D I N NN G G
UUUU P GG R R A A DDD IIIII N N GG
TTTTTTTT W W W GGGGGG SSSSSSS
TT W W W W GG SS
TT W W W W GGGGGGG SSSSSS
TT W W GG GG SS
TT W W GGGGGG SSSSSSS
(And other General Information about the card)
Information about the TWGS Accelerator card for the Apple IIgs.
Including Instructions on how to make it FASTER. UPGRADING a Transwarp
Cards' speed is EASY. 2 parts need to be replaced (these parts are
currently available, and easy to get ahold of.) Absolutely no
electronics experience or soldering is needed.
TWGS1 : The Transwarp IIgs card.
_______________________________________________________________
/ ^ O :::::::::::: | GALs | |XXX|
/ ------ __________________ |______| |XXX|
/ |YYYY| | | ----|
|< |YYYY| | Cache | _________________|
| ------ | Piggy Back | | | |
| | | | GALS | GALs |
| _________|______ | |_________|______|
|______________|____________|___|__________|_ __|
IIIIIIIIIIIIIIIIIIIII
XXX = Clock Oscillator, 1/2 size. The speed of the
Accelerated
XXX = Transwarp IIgs is equal to the Oscillator speed Divided
by 4
YYYY = Fast Processor Chip. This is the CPU of the TWGS.
YYYY = It is a 65816 CPU and is Upgradeable to 10-15 MHZ
GALs = Chips you don't have to worry about. Read Table of
contents item 13 if you want to know more about them.
Cache = You need at least ROM version 1.5 to go faster.
Piggy = This board Has the SRAM, and ROM. You can
Back = Upgrade the Cache on this board (32k maximum)
O = Green LED that Indicates Accelerated speed when lit
III = Slot connector. This is inserted into a slot in the
IIgs.
See the long skinny rectangle Below and to the left of the Cache Piggy
Back? This is where the CPU connector cable connects to the TWGS.
Also, there is a series of :::: (Colons) on the top of the card to the
right of the LED indicator light. This is a black connector, with two
rows of pins. I was told this was a TESTING connector, and that
Applied Engineering could hook up some type of Testing Machine to check
for problems on the TWGS.
ONE last thing, about ASCII picture inaccuracy. See the left end of
the board? It is clipped off at a 45 degree angle. A real Transwarp
is cut like this, but the cut starts a little to the left of the LED
(see the arrow pointing to the edge of the card? The cut continues to
the Left edge of the card (see the other arrow?)
-----------------------------------------------------
-----------------------------------------------------
TABLE OF CONTENTS
1) Text representation of the Transwarp (A picture)
2) Explanation of what the TWGS card is.
3) HOW DOES IT WORK to speed up your computer??
4) What can you upgrade on your TWGS to make it faster?
5) Speed Comparisons of cache upgraded TWGS cards.
6) Speed Comparisons of processor speed upgraded TWGS cards.
7) HOW TO upgrade your TWGS processor speed to at least 10 mhz.
8) HOW TO upgrade your TWGS cache.
9) How fast will a Transwarp go?
10) Other information sources.
11) Where did All of this information come from?
12) Why did I do this when the Information can be found elsewhere?
13) About the GAL chips, and why you don't have to worry about them.
(Search for TWGS#. Substitute the table of contents number that you
want to view for the #)
-----------------------------------------------------
-----------------------------------------------------
TWGS2
Explanation of What the TWGS card is.
The Transwarp IIgs
==================
PLEASE NOTE: I have ROM version 1.5 at the moment. The CDA (as well as
other ROM specific features) *may* be different in other ROM versions.
The Transwarp IIgs is an Accelerator card for the Apple IIgs that
boosts the overall speed above the normal 2.8 mhz for the stock IIgs.
The Transwarp cards came stock with 7mhz speed, and an 8k cache. (READ
section 3 for information on the Cache)
The card is installed in a slot, the CPU is removed from the
motherboard of the IIgs, and a ribbon cable attaches the Transwarp card
to the Processor receptacle.
Upon booting a IIgs with a Transwarp installed, the word "Transwarp"
is zoomed in to the screen (starts Tiny on the bottom of the screen,
and increases in size as it scrolls up on the screen)
After Transwarp appears, GS jets in from the side with a trail of
rainbow color behind it, stops in the center of the screen, and then
dissapears off the other side of the screen.
The Graphics are accompanied by a sound similar to the Road Runner
noise (whoooooosh)
Ok, now that the Transwarp equipped IIgs is booted, the computer
runs as it normally would, with increased speed. That is all this
board does. Increases the speed of the IIGS, and does not
interfere/enhance anything else.
The cards' operation is absolutely transparent to the normal
operations of the computer (except things Zoooooom really fast) I have
never heard of ANY compatibility problems. (Some games will run TOO
fast!)
The Transwarp does have a few features which can be accessed from
the CDA menu (Press Control-apple-Escape to access this menu)
On the CDA menu, you will see a Menu selection called "Transwarp GS"
Select this menu Item.
A new menu appears with the following:
Speed Control --Lets you change speed of the card, Transwarped
(7mhz) or IIgs normal speed (2.8 mhz)
Configure --There is an AppleTalk enabling feature and you
can also
Turn the Startup Graphics and sound ON or OFF
Quick Self Test --Test the TWGS for errors, bad chips
Continous Self Test --Same as quick test, but It repeats over and over
until
you press a key.
About Transwarp GS --View the Credits....Who worked to bring you the
TWGS
(The ROM VERSION, copyright notice, and Applied Engineering are printed
at the bottom of the screen)
-------------------------------------------------------------------
-------------------------------------------------------------------
TWGS3
How does it speed up your computer?
THE FOLLOWING WAS CUT FROM THE TWGS UPGRADE STACK
The TransWarp GS is a caching accelerator. It works by reading the
contents of motherboard memory into a small area of high speed memory
on the accelerator called a cache, hence the term caching accelerator.
Even though a caching accelerator never accelerates more than a small
portion of memory at any one time, a caching accelerator is able to
accelerate any area of memory space up to 16 megabytes. It relies on
the laws of probability which predict that a tiny fraction of actual
memory is used the majority of the time.
The accelerator operates in three phases, each of which take up
time. It must first capture the code that it will accelerate. Then the
card's CPU excecutes the captured code at the accelerated speed.
Finally, the accelerator must change motherboard memory as indicated by
the code processed in the cache. On a GS computer, the last phase is
especially critical because the speed of the motherboard memory is
limited to 2.8, 2.6, or even 1.0MHz depending on which area of memory
is addressed (2.8 for ROM, 2.6 for fast RAM, and 1.0 for screen display
and banks designated for IIe emulation). The TransWarp GS is designed
to improve all three phases of acceleration.
Capture and Execution:
The TransWarp GS divides its cache into two parts called DATA and
TAG. The DATA area contains the code that will be accelerated. The
TAG area contains the address of the original code. The accelerator
looks in the tag area to determine whether the code that it will
execute has already been cached, or whether it must capture it first.
On the Apple II, both 8-bit and 16-bit TAGs are supported. All GS
accelerators use 16-bit tags. Accelerators with an 8-bit TAG are
limited in the range of memory that they can accelerate to a function
of the size of the data area. For example, the ZipChip accelerator for
the 8-bit Apple II's use an 8-bit TAG, so its built-in 8K of cache can
only accelerate 1.5MB of memory. The TransWarp GS accelerator, in
contrast, can accelerate 16MB of memory, no matter what the size of its
cache is because it uses a 16-bit TAG. This is important because adding
more memory to a GS motherboard will not degrade the performance of the
TransWarp GS (and a GS with an AE RamKeeper and two narrow body 8MB
memory boards, like the Sequential Systems RAM GS Plus, can have 16MB
of memory P 8MB as system RAM and the rest divided between ROM storage
and the RAM disk).
The downside of a 16-bit TAG system is that it requires twice as
many chips as the 8-bit system. This is why 128K worth of cache chips
from a PC's L2 cache turns into 64K worth of cache when installed in a
Zip GS (the other accelerator for the GS). In a complex and memory
intensive computer like the GS, however, the increased efficiency of a
16-bit TAG system more than outweighs the need for extra chips.
Each time the TransWarp GS needs to execute some code, it checks the
TAG area to see if the code is already in cache memory. If the code is
in the cache, the card executes the code and all is well. This is
called a "hit." If the code is not present in the cache, the
accelerator captures the code from the motherboard RAM and stores its
address in the TAG area. The TransWarp GS can then execute the code.
This is called a "miss" because the capture and store operations slow
performance significantly.
A 100% efficient cache is one which never suffers a "miss."
Increasing the size of the cache increases the percentage of hits,
which is why more cache means better performance. However, while
performance initially increases dramatically going from a small cache
to a larger one, at a certain point you are going to notice only
fractional increases in speed by continuing to increase cache size. My
own tests (using a Zip GS) show that performance pretty much levels off
at 16K of cache for most GS programs. While 8K of cache is slower than
16K, 32K and 64K of cache is not much better than 16K. The TransWarp
GS is factory installed with 8K of cache, but you can still buy a 32K
cache upgrade.
Writing back to Motherboard Memory:
Many of the instructions executed in the cache affect parts of
motherboard memory that have not been cached. The TransWarp GS uses a
technique called "write back" to update motherboard memory without
slowing down acceleration. The "write back" technique stores the
instructions which order changes to the motherboard memory in a buffer
on the accelerator. These instructions are executed in the background,
updating the motherboard memory at the required slow speed while the
accelerator continues to execute additional instructions at the full
accelerated speed in the foreground. Because the TransWarp GS uses
multiple write back buffers, its CPU rarely needs to slow down to match
the motherboard's standard speed.
The use of "write back" technology is especially important in a GS
because the IIGS's video memory operates at a slow 1MHz to maintain IIe
compatibility. A TransWarp GS can update the screen in the background
while the user scrolls through a document, leaving it free to process
the actual code that orders the scrolling at accelerated speed. It is
because of the write back technique that the TransWarp GS is able to
accelerate graphics operations instead of having completely suspend
acceleration during screen updates.
THE ABOVE TEXT WAS CUT FROM THE TWGS UPGRADE STACK
***END OF INFORMATION COPIED FROM THE TWGS UPGRADE STACK***
-------------------------------------------------------------------
-------------------------------------------------------------------
TWGS4
What can you Upgrade on your TWGS to make it faster?
You can upgrade the Cache size on your Transwarp IIgs, or the
processor. The cache can be 8k (stock) or 32k (Fully upgraded). The
processor can be sped up from the stock TWGS 7mhz speed to as high as
15mhz.
-------------------------------------------------------------------
-------------------------------------------------------------------
TWGS5
TWGS6
Speed Comparisons of Upgraded TWGS cards
_____________________________
�������������������������������������
What kind of performance increase can one expect?
THE FOLLOWING WAS CUT FROM NATHAN MATES ACCELERATOR FAQ
��
This is just to give you a rough estimate of how much faster you
might
�� go...
��
������� BenchMark v5.0 results:
������� cpu�������� stock�� twgs�� twgs�� twgs����� zip��� zip�� zip
������� version��� ROM 01�� 1.8s�� 1.8s�� 1.8s��� 1.0.2� 1.0.2� 1.0.2
������� cache/spd�������� 32k/15 32k/15 32k/15�� 64k/?? 64k/?? 64k/??
������� clock spd���� 2.8���� 15� 13.75�� 12.5������ 16���� 15���� 14
����������������� ======= ====== ====== ======�� ====== ====== ======
������� Sieve����� 410.00� 99.00 108.00 117.00��� 98.00� 99.00 110.00
������� String��� 1151.20 270.00 292.00 303.67�� 259.00 262.00 282.00
������� Float 1��� 472.00� 92.33� 87.00 111.33�� 123.00 128.00 135.00
������� Float 2�� 1535.00 317.00 394.00 381.67�� 395.00 415.00 432.00
������� Fibinacci 2006.00 605.00 634.00 645.33�� 507.00 523.00 548.00
������� Integer�� 1553.40 307.00 330.00 346.67�� 420.00 431.00 443.00
������� Dhrystone���� 236�� 1136�� 1063�� 1000������ NA���� NA���� NA
��������������� *���������� 1351��������� 1183���� 1282���� NA���� NA
������� * Dhrystone v1.1 re-compiled under ORCA/C v2.0.1
�� If you look at the numbers, a 12 MHz or faster TWGS/Zip will make
�� everything just about 4x faster than a stock //gs.
��
������� System Software 5.0 QuickDraw II improvement test:
������� stock //gs:���� 5648 ticks
������� TWGS 15 MHz:��� 1332 ticks (over 4x faster than stock)
���� _________________________________________________________________
�������������������������������������
THE ABOVE WAS CUT FROM NATHAN MATES ACCELERATOR FAQ
The Following is cut from a post to CSA2 made by Rubywand
********************************************************
John Link charted some comparisons in 1991 involving nine setups:
no-TWGS, and 7, 8, 9, 10mHz boards before and after the 8kB-to-32kB
cache upgrade. He used three benchmarks:
1. time to calculate page breaks in a 218-page Appleworks document
2. time to scroll through a 39-page Awks-GS document
3. time to compile 4800 lines of MD-BASIC source code
The chart shows that a 7mHz TWGS with the 32kB cache performs
slightly better than a 10mHz TWGS with 8kB cache on tests 1 and 3; it is
a bit slower on test 2.
For a 7mHz 8kB TWGS, the speed gain for the 32kB cache upgrade is
roughly 33% to nearly x2.5 plain GS speed.
For a 10mHz 8kB TWGS, the speed gain for the 32kB cache upgrade is
roughly 33% to about x3.25 plain GS speed.
One nice feature of upgrading cache is that you get a good
performance boost without the concerns usually assorted with a
significant increase in clock speed.
******************************************
The Following is cut from an Email from Joachim Lange of ///SHH
Systeme, which is the company that produces the 32k Cache Upgrade
*****************************************
"The larger cache size gives you more speed without the need of
increasing
the processor's clock frequency. The overall gain in speed is about
20..30
per cent, however the Finder feeling is a lot more "snappy"."
*****************************************
-------------------------------------------------------------------
-------------------------------------------------------------------
TWGS7
HOW TO upgrade your TWGS processor speed to at least 10 mhz.
NOTE:
Almost every Transwarp GS will go 10MHz. Try 10MHz, and if it works
ok, buy another higher MHz oscillator ($4.00) and see if you can puch
it faster! The 10MHz upgrade is the most likely to work on all TWGS's
witout further modification.
WHAT YOU NEED TO UPGRADE:
1) Transwarp IIgs with ROM version 1.5 or greater (With the IIGS
turned on, press CONTROL-Apple-ESCAPE And go to the Transwarp CDA The
ROM version will be displayed near the bottom of the screen)
THE Following TEXT WAS CUT FROM THE TWGS UPGRADE STACK
Version 1.5 ROMs do have one quirk: at speeds faster than 8MHz, the
speed self-test reports false error messages. You can ignore these
error messages.
THE ABOVE TEXT WAS CUT FROM THE TWGS UPGRADE STACK
***END OF INFORMATION COPIED FROM THE TWGS UPGRADE STACK***
2) A high speed 65816 chip
3) A 1/2 size Clock Oscillator that is 4X the megahertz you want to
your TWGS to run.
___________________________________________________________________
| Digikey Part # | Clock Oscillator speed | TWGS speed |
|------------------|------------------------|----------------------|
| CTX175-ND | 40 MHz | 10 MHz |
| | 48 MHz | 12 MHz |
| |*******55 MHz******* | ***13.75 MHz****** |
| |*******60 MHz******* | ******15 MHz****** |
|__________________|________________________|______________________|
*** = WARNING! 15MHz modification should be treated as
"experimental"-
*** = i.e. an upgrade which may require increasing board voltage
and/or going to faster RAM. John Link says that you can go
to 12.5MHz with processor and Oscillator replacement,
including keeping the 45ns RAM. .) However, starting at
13.5MHz, John had to increase board voltage.
----------------------------------------------------------------------
WHERE DO YOU GET THE PARTS TO UPGRADE?
Transwarp GS is no longer manufactured. Applied Engineering has gone
out of business. You can find them *used* in the classified ads, or on
CSA2 marketplace newsgroup.
You can get the 65c816 -14 PLCC chip from the Western Design Center
Their URL is:
***WESTERN DESIGN CENTER
http://www.wdesignc.com/
E-mail: information@wdesignc.com
Phone: 602-962-4545
Fax: 602-835-6442
Address: Western Design Center
2166 E. Brown Road
Mesa, Arizona 85213
E-mail: information@wdesignc.com
You can buy 1/2 size Oscillators from Digikey (Price= $3.25). Their
URL is:
***DigiKey
http://www.digikey.com/
Telephone USA: (800)344-4539
Local and International Tel: (218)681-6674
FAX: (218)681-3380
Address: Digi-Key Corporation
701 Brooks Ave. South
Thief River Falls, MN 56701-0677
You can also get these Oscillators from almost any Electronics supplier
or store. (Radio Shack included, but they are expensive)
----------------------------------------------------------------------
INSTRUCTIONS::::
THE Following TEXT WAS CUT FROM THE TWGS UPGRADE STACK
"Following the instructions in this document, you will be able to
get your TransWarp GS running at 10MHz. Most TransWarp GS cards can go
all the way to 15MHz, but at those high speeds success will depend a
lot on the particular card, GS, and configuration of the computer.
However, all TransWarp GS users should be able to upgrade to 10MHz"
THE ABOVE TEXT WAS CUT FROM THE TWGS UPGRADE STACK
***END OF INFORMATION COPIED FROM THE TWGS UPGRADE STACK***
Refer to the Picture at the top of this article for component location.
Ok. TURN OFF your IIgs. Leave it plugged in because the Ground pin
in the plug gives your computer good grounding.
Open the case. Touch the power supply to ground yourself.
Remove your Transwarp Card. Be careful not to bend the pins on the
processor plug on the TWGS. Put the Transwarp card in a safe place.
Remove the Old 65816 with a 44pin PLCC chip puller.
THE FOLLOWING TEXT WAS CUT FROM THE TWGS UPGRADE STACK
If you are careful, you can use a bent paper clip to remove the chip.
Straighten a fairly strong paper clip and bend the last inch to
about 90 degrees. Each corner of the CPU socket has a slot wide enough
to admit a paper clip. Insert the bent end into one of the four slots
in the socket until it is underneath the chip and gently pry upward
using the paper clip as a lever. Repeat the process in each of the
other corners until the chip is free enough to be removed."
THE ABOVE TEXT WAS CUT FROM THE TWGS UPGRADE STACK
***END OF INFORMATION COPIED FROM THE TWGS UPGRADE STACK***
Stick the new 14mhz chip into the socket, making sure it is
positioned correctly. The correct position is with the cut off edge in
the upper left hand corner of the socket. Press gently until the new
chip is seated in the socket.
Now, remove the Clock oscillator, gently pulling with your fingers.
Time to put in the new oscillator.
THE FOLLOWING TEXT WAS CUT FROM THE TWGS UPGRADE STACK
If the new oscillator comes in a metal case, install it with the
sharp corner in the upper left hand position. If the new oscillator
has a plastic case, install it with the indent facing up toward the top
of the card.
THE ABOVE TEXT WAS CUT FROM THE TWGS UPGRADE STACK
***END OF INFORMATION COPIED FROM THE TWGS UPGRADE STACK***
Plug the new oscillator into the socket, making sure it is
positioned correctly.
Re-Install the TWGS with the power turned off, and boot up!
--------------------------------------------------------
--------------------------------------------------------
TWGS8
How to upgrade your TWGS cache.
Important note about 32K upgrade
================================
The TransWarp GS firmware version 1.5 that came with the TransWarp
8K version does not work with 32K cache boards. You absolutely need
v1.7 or v1.8 for 32K cache operation.
Scroll down to the bottom to view the Advertisement that ///SHH Systeme
has for their TWGS upgrades.
Contact ///SHH Systeme. They sell the 32k upgrade boards and the
upgrade ROM that is required.
Email:
Joachim Lange <lange@tasha.muc.de>
Visit the Web site at:
http://users.ids.net/~kerwood/shh.html
Or, Write to:
SHH SYSTEME,
Dipl. Ing. Joachim Lange,
Bergstrasse 95,
82131 Stockdorf,
Germany.
-----------------------------------------------------------
-----------------------------------------------------------
TWGS9
How fast will a Transwarp go?
THE FOLLOWING WAS CUT FROM THE TWGS UPGRADE STACK
I've found that a 13.75MHz GS operates non-math intensive operations
faster than a 25MHz '486 PC. I use both regularly and a fast GS is
simply more efficient at running word processors and page layout
programs than a slow PC. Specifically, AppleWorks GS v1.1 on a
13.75MHz GS runs much faster than Microsoft Works (Win 3.1 version)
under Win 95 on a 25MHz '486 PC. For math intensive operations,
though, the GS lacks a math coprocessor, which is a disadvantage. This
shows up in graphics processing applications and spreadsheets. For
these operations, a math coprocessor card like the Floating Point
Engine or Number Cruncher will take the GS to the next level. The
Number Cruncher is still available from its German maker as a special
order product (you need to gather 10 people and order at once for the
designer to make a batch). A TransWarped GS with a 10-15MHz processor
_and_ a math coprocessor will still knock out many PC computers and
Macs. Amazing performance for a >decade old computer. (It is
difficult to remember that the GS came from the era of the Mac Plus and
the Turbo XT/6MHz AT since they wouldn't even be in the ballpark of a
souped up GS! :)
The GS that I use is powered by a Zip GS rather than a TransWarp GS
accelerator, however. Tests show that for a given speed, a TransWarp
GS outperforms a Zip GS. For most tasks, a 12.5MHz TransWarp GS is
faster than a 13.75MHz Zip GS. However, the stock TransWarp GS card
has only 8K of cache while my GS vs. PC comparisons were done on a Zip
GS with 16K of cache. Thus, the comparison should still be valid; a
TransWarp GS with 8K should run about as fast as a Zip GS with 16K, the
two factors (increased efficiency, but less cache) cancelling out.
THE ABOVE TEXT WAS CUT FROM THE TWGS UPGRADE STACK
***END OF INFORMATION COPIED FROM THE TWGS UPGRADE STACK***
-----------------------------------------------------------
-----------------------------------------------------------
TWGS10
Other information sources:
THE HyperCard TWGS Upgrade stack (TWGSupgrade.SHK) can be found at:
http://ground.isca.uiowa.edu/apple2/apple16/Hypermedia/Hypercard/
THE HyperCard TWGS Upgrade stack is Copyright 1997 by Scott Gamon. It
is FREEWARE
(To View this stack on your IIgs, download the runtime player,
hcgsplayer.shk from:
http://ground.isca.uiowa.edu/apple2/apple16/Hypermedia/Hypercard/)
Comp.sys.apple2 newsgroup
-----------------------------------------------------------
-----------------------------------------------------------
TWGS11
Where did all of this information come from?
Mostly from the HyperCard TWGS upgrade stack. (TWGSupgrade.SHK, found
at http://ground.isca.uiowa.edu/apple2/apple16/Hypermedia/Hypercard/)
THE HyperCard TWGS Upgrade stack is Copyright 1997 by Scott Gamon. It
is FREEWARE
Some of it came from the posters comp.sys.apple2 newsgroup. (Rubywand
was helpful)
I "drew" the picture with my Transwarp IIgs right in front of me. I
think I did a good job, and almost everything was in the correct
place/in proportion.
I also typed up the Explanation of the TWGS (table of contents # 2)
I gathered some information about speed comparisons, and I will
continue to search for more charts, tables, and graphs comparing speeds
of upgraded TWGS cards.
-----------------------------------------------------------
-----------------------------------------------------------
TWGS12
Why did I do this when the Information can be found elsewhere?
I thought about speeding up my TWGS many times...but the info I have
found includes instructions that I don't even want to start to try.
I drew a nice ASCII picture of the TWGS.
Also, I have never seen a COMPLETE document about the TWGS. I looked
around and gathered all the information I could find, and stuck it into
one document.
-----------------------------------------------------------
-----------------------------------------------------------
TWGS13
About the GAL chips, and why you don't have to worry about them.
THE FOLLOWING TEXT WAS CUT FROM THE TWGS UPGRADE STACK
"Here is some interesting trivia: look in the above diagram which
points out the TransWarp GS's Generic Array Logic (GAL) chips. Once
upon a time (before 1992), the Western Design Center could not make
65C816 chips that reliably ran above a speed of 7MHz. In an effort to
make faster chips, the company produced models designated as
"engineering chips" (identified by part number W65C816PL-ENG). These
chips varied in their top speed and tended to go no more than 9MHz to
10MHz reliably. They were really not much better than the production
parts. It was discovered that chips based on this older design had
difficulties executing 16-bit instructions above a certain speed. The
TransWarp GS's GALs were designed to intercept these instructions and
add extra cycles to slow down execution and overcome the processor's
limitations. Apparently, when Western Design Center came out with
their engineering chips, hitting 10MHz produced even more 16-bit
instructions that had trouble executing. Thus, for a time Applied
Engineering offered a replacement set of GALs to allow the TransWarp GS
to reach high speeds with those chips.
Applied Engineering is now gone, so what do users do about the GALs?
Nothing. Since the time of the engineering chips, the Western Design
Center had Sanyo completely redesign the 65C816 (chips of the new
design all have an "S" in their names, incidentally). The new chips
properly reach speeds of 16MHz (according to the technical
specifications on WDC's world-wide web page). 16-bit and 8-bit
instructions fail simultaneously if the chip is overclocked. This
means that the GALs are no longer necessary. A stock TransWarp GS with
ROM version 1.5 can now be upgraded to 10MHz-15MHz speeds without
replacement GALs."
THE ABOVE TEXT WAS CUT FROM THE TWGS UPGRADE STACK
***END OF INFORMATION COPIED FROM THE TWGS UPGRADE STACK***
---------------------------------------------------------------
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