Re: TWGS

[Liam Busey <liam1@ix.netcom.com>]

CBS wrote:
> 
> I was looking at my TWGS earlier.  I am interested in other people's
> card version numbers.  If you don't mind, go to the TWGS control > panel, and jot down the following info:  Version, revision, You'll > have to look at the card to get the:  DATE, GAL versions.
> 
> Sagochangi:    TWGS: version 8H, rev 1.4x  ????,2A,??,??,??,??,??,??
> 
> Mine:          TWGS: version 8S, rev 1.5w 1989 1A,2B,3B,4A,5A,6A,7A,8A
> 

Mine (Liam):     TWGS: version 8S, rev 1.5x 1989 1A,2A,3B,4A,5A,6A,7A,8A

Note: the version number in the control panel said version 8S while the
ROM was marked 8H.

> What exactly are GAL chips?  I know what they do, but are they IC's?
> Are they ROM's?

GAL = Generic Array Logic

They're a type of PLD (Programmable Logic Device) manufactured by
Lattice Semiconductor. They're kind of like eproms except they're logic
instead of data and they can only be programmed once. GALs as well as
chip ROMs are ICs.

> The GAL's slow down certain instructions that were 'broken' on the > older CPU chips.  The instructions wouldn't operate in high speed, so > the chips slowed those instructions down.
> 
> What happens if you run a TWGS without *any* GAL chips?  No slow down,
> but will the card operate?

The card won't operate properly because you'd be breaking the circuit.

> I've read here that the GAL's are hard to copy.  Why is this?  Besides
> the obvious reason of copyright (held by a now bankrupt, long gone
> company), what is stopping Apple II'ers from copying the fastest GAL
> chips?

Unlike ROMs, GALs can't be dumped. ROMs contain data while GALs
manipulate data with the logic inside of them. However one might be able
to make clone of a GAL if they could figure out what signals go which
pins, test every possible combination and record the results, design a
clone using the data from your tests, and then find a GAL burner to make
your clone. Needless to say, this would be a royal pain in the arse.

> From Tony Diaz's website, it looks like you want the REV *A* GAL > chips. (quoted from apple2.org/TWGS):
> "". Using a complete set of Rev A GALs in your TWGS, along with the
> Sanyo '816 design allows for un metered flow of instructions through
> your TWGS""
> 
> REV A GALS= ***UNMETERED***, according to Tony Diaz.
> 
> It sounds to me like
> 
> (FOLLOWING IS THEORY, based on the facts I've collected)
> ***************************************************************
> the REV A Gals were made when the FIRST 65816 chip came out.  This > would mean no bugs that you'd have to slow it down for, thus the A > gals. Then they sped up the CPU, but not flawlessly, so they had to 
> slow down certain instructions in order for them not to crash the > CPU/TWGS card. That required the addition of the B (and other???) gals
> ***************************************************************

I don't believe the original 65816 was ever sped up. I think WDC just
had certain batches that were more reliable at higher speeds than
others. Kind of like CRT quality in monitors.

Liam Busey