TWGS vs ZipGS (was Re: WOLF3D fot A2 GS)

[spec@vax2.concordia.ca (Mitchell Spector)]

In article supertimer@aol.com (Supertimer) writes...

>spec@vax2.concordia.ca (Mitchell Spector) wrote:
>
>>ZipGS is clearly the superior product.
>>
>>TransWarp GS
>>------------
>>- Original firmware does not support beyond 6.25 MHz
>
>The great majority of TWGS came with 7Mhz CPUs and the
>ROM v1.5 firmware that supports speeds up to 15Mhz.

    I was just simply stating a fact. There ARE boards out there
with the original ROM (v1.4) and cannot be upgraded unless you
replace the daughterboard. There is no such thing as old Zip GS
that cannot be upgraded, so this definitely applies as a con.

    My own TWGS has the original ROM, making my board virtually
worthless to me except for parts. The only way to get a new ROM
is to order a complete daughterboard replacement, and that costs
more than a complete TWGS. In fact, I discovered it is cheaper
to just purchase a new TWGS than ordering replacement parts and
that is what I'm about to do.

>>- Not DMA compatible
>
>Says who?

    Um, this is common knowledge. The TWGS does not properly (or
at all for that matter) support DMA, which was just _one_ of the
things that made the ZipGS more attractive.

>>- Compatibility issues with certain software and hardware
>
>Not!  It is just as transparent as the Zip GS.

    Well this is my observation, at least with the original ROM
firmware. When I try and run ProTERM 3.1, it displays a garbled
screen and tells me some obscure ProDOS error. If I remove the
TWGS, this problem disappears (and it certainly does not occur
with my ZipGS). I can just imagine what other oddities it may
cause with software.

    With hardware, there's the DMA issue again. It does not get
along very well with a RamFAST SCSI or memory cards which try
and do DMA. My ZipGS, OTOH, works beautifully with DMA enabled.

>>- Poor stability (newer CPU cable and cooling may fix this though)
>
>Quite stable.

    Not mine. It crashes and locks after the system has been on
a couple of minutes. Mind you, I do have one of the cards with
the original CPU ribbon cable (no black dot on it) and this may
very well be the cause.

>>- Requires newer GAL chips for high speeds with pre-1993 65C816's
>
>And who is using such pre-1993 chips anymore?  The current
>65C816s don't need any such GAL replacements.

    Once again, I am just stating a fact. The ZipGS does not
need chips replaced depending upon the manufacturing date of
the 65C816 plugged in. All my 65C816's--with the exception
of the -14 rated one in my ZipGS--are all pre-1989 chips as 
it happens.

>>- Simple to upgrade (daughterboard and oscillator socketed)
>>- ROM based software to adjust speed/configure of card
>>- More efficient caching method, runs slightly faster
>
>Yup.  You can still get a blank daughterboard that has
>skinny SRAM sockets.

    The daughterboard replacements are only available through
SHH Systems overseas, and their prices are quite expensive if
you ask me. Fortunately, as you mentioned, this is only an
optional upgrade.

>>>If your TWGS card is capable of 15Mhz, it will go at that speed
>>>without soldering. Swapping SRAMs maybe, but never soldering.
>>
>>    Aren't you required to cut some trace on the back of the
>>board? That is much easier than soldering, but still requires
>>some degree of skill and a steady hand.
>
>Nope.  You need to cut the trace when upgrading to a larger
>cache, but you DON'T need to cut the trace when upgrading
>CPU speed.  Also, the SRAMs supplied on the stock daughterboard
>are quite usable at speeds of up to 12.5Mhz.
>
>That means to push a TWGS to 12.5Mhz, you just swap the CPU
>and oscillator.  I've read of some units that go faster.

    That is one feature of the TWGS which gives it a definite
edge over the ZipGS. That makes it almost as simple as over-
clocking a 486 or Pentium PC (too bad it didn't use jumpers
to save the hassle of looking for oscillators to plug in, but 
I can live with that if I don't need to solder). :)

    The TWGS does offer some minor advantages (upgrades, speed
and built-in configuration) but I still stick with my feelings
on the ZipGS being the better of the two accelerator products.
I'm sure you'll find I'm not in the minority in thinking that
either. 

Mitchell Spector
spec@vax2.concordia.ca