Re: ZipGS on eBay

["PZ" <skierpaul@yahoo.com>]

Yeah, thats right, for a TWGS you just need a WDC 65SC816 -14 and a
faster XTAL. The info you have is solid.

The firmware has nothing to do with speed, only with Cache size.  A
v1.7 or more preferably a v1.8 ROM is needed to upgrade to 32k of cache
in addition to the minor trace mods on the cache card.  Like I said,
the stock 45ns cache RAM on the TWGS works in most cases for upgrades
to the 12-13mhz range.

There are a couple additional mods that need to be made in addition to
faster cache ram, for the card to run stable.  AE started implementing
these changes on some of the last TWGS they released.

- Paul

BTW, I get my information from all of the testing/modding I've done to
get a TWGS to boot GS/OS at 18.75mhz.


aiiadict@gmail.com wrote:
> I wrote:
> > I don't know where you guys get your information..
> >
>
>
> Here's where I got my information:
>
> #1)4 TWGS boards upgraded by myself since 1998, by
> doing the following:
> ---install WDC 14Mhz 65816 CPU
> ---install 50Mhz oscillator (50/4 = 12.5)
> ---install new cpu cable
> ---if IIgs is full of cards, get heavy duty power supply
>
>
> #2) I didn't just start hacking and hoping...  I read this
> group and other Apple II users were having success,
> so I decided to try it:
>
> From: superti...@aol.com (Supertimer)
> Subject: Re: WOLF3D fot A2 GS
> Date: 1998/08/18
> Message-ID: <1998081803060500.XAA29660@ladder01.news.aol.com>#1/1
> X-Deja-AN: 382161641
> References: <17AUG199816583182@vax2.concordia.ca>
> Organization: AOL http://www.aol.com
> Newsgroups: comp.sys.apple2
> X-Admin: n...@aol.com
>
>
> >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.
>
> >- 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.
>
>
>
> AND:
>
>
> From: superti...@aol.com (Supertimer)
> Subject: Re: ZipGS or TWGS, which is better?
> Date: 1999/07/20
> Message-ID: <19990720011418.19467.00000359@ng-ba1.aol.com>#1/1
> X-Deja-AN: 503008479
> References: <932285313.788.25@news.remarQ.com>
> Organization: AOL http://www.aol.com
> Newsgroups: comp.sys.apple2
> X-Admin: n...@aol.com
>
>
> The main disadvantage of the Zip GS is that on most cards, you
> need to change the cache RAM chips in order to go into speeds of
> 12.5Mhz or greater.  The regular TWGS comes with cache RAM
> chips fast enough to go 12.5Mhz (as mine does).  But the speed
> of the cache RAM chips provided on the Zip GS from the factory
> will be too slow in most cases to get 12.5Mhz or greater.
>
>
>
>
> AND:
>
>
> From: mys...@direct.ca (Herbert Fung)
> Subject: Re: New chip in TWGS
> Date: 1999/09/12
> Message-ID: <l1FC3.4268$O83.392891@t2.direct.ca>#1/1
> X-Deja-AN: 523970669
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> X-Complaints-To: abuse@direct.ca
> X-Trace: t2.direct.ca 937106641 216.66.144.104 (Sat, 11 Sep 1999
> 20:24:01 PDT)
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> Reply-To: mys...@NOSPAMdirect.ca
> NNTP-Posting-Date: Sat, 11 Sep 1999 20:24:01 PDT
> Newsgroups: comp.sys.apple2,comp.sys.apple2.marketplace
>
>
> The CPU itself can probably be pushed to 20MHz but according to others
> you'll probably need faster than 15ns SRAMs. The fastest reliable speed
>
> for stock TWGS's I think was 12.5MHz.
>
>
>
> AND:
>
>
> From: Bryan Villados <news...@macgeek.org>
> Subject: Re: New chip in TWGS
> Date: 1999/09/13
> Message-ID: <120919992123213065%news001@macgeek.org>#1/1
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> <Pine.GSO.3.95.iB1.0.990912160628.16475A-100000@halifax.chebucto.ns.ca>
> <37dc12f3.5031531@news>
> <Pine.GSO.3.95.iB1.0.990912232318.23296B-100000@halifax.chebucto.ns.ca>
> Mail-Copies-To: nobody
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>
>
>
> If you only change the CPU and left the oscillator at
> 28Mhz, you are in effect underclocking the fast CPU
> at 7Mhz.
>
>
> What you have to do is replace the current oscillator,
> 28Mhz (which means 7Mhz CPU speed) with a faster
> one.  32Mhz oscillator means 8Mhz CPU.  36Mhz=4Mhz.
>
>
> I suggest a 40Mhz and a 50Mhz one for testing 10Mhz
> and 12.5Mhz CPU speeds and perhaps a few faster
> ones to see how fast your TWGS can go.
>
>
>
>
> AND:
>
>
> From: superti...@aol.com (Supertimer)
> Subject: Re: New chip in TWGS (sources for oscillators)
> Date: 1999/10/25
> Message-ID: <19991025013634.01524.00000793@ng-fp1.aol.com>#1/1
> X-Deja-AN: 540204695
> References: <cornelio-2410991116360001@dt050n7c.san.rr.com>
> Organization: AOL http://www.aol.com
> Newsgroups: comp.sys.apple2
> X-Admin: n...@aol.com
>
> corne...@san.rr.com (L. Cornelio) wrote:
>
> >superti...@aol.com (Supertimer) wrote:
> >
> >>If not, I suggest getting the 50Mhz and 40Mhz units.
> >>12.5Mhz TWGS (50Mhz oscillator) almost always
> >>works, but with a 40Mhz unit, you can fall back on
> >>10Mhz operation if necessary.
> >
> >FYI, my ZipGSX works fine w/ a 40 mhz & no chip swap.
> >Does that maybe imply that w/ a chip sway 50 or even 60 will work?
>
> Very likely yes.  Especially the 50.  What was the Zip
> clocked at before?  If you have the 8Mhz processor of
> the Sanyo design, you have a very overclockable chip.
> It does not hurt to give it a try.
>
> >I was wondering which cards were considered more
> >"easily upgradeable" the TWGS or the Zip.....
>
> It depends.  TWGS is simpler to upgrade all other
> things considered.  It has cache RAM fast enough
> so that to upgrade it usually involves changing only
> the oscillator and the CPU.  For minor speed
> upgrades, sometimes only the oscillator needs to
> be replaced.
>
> But the TWGS is older.  It came with either 6Mhz
> or 7Mhz CPUs of the older design.  The 6Mhz
> version was not very overclockable.  Thus, for
> major speed upgrades you need a new CPU for
> the TWGS.
>
> The Zip GS started with CPU chips of the type used
> in the TWGS, but the Zip GS survived long enough
> that they started using the Sanyo versions of the
> chips.  These came in either 8Mhz or 14Mhz
> versions.  These were VERY overclockable.  Some
> people have pushed the 8Mhz chip to 15Mhz, for
> example.  So if you have the "good" 8Mhz chip,
> you can often avoid a new CPU and thus save a
> step compared to the TWGS.
>
> BUT if your Zip GS started out with the older
> 7Mhz CPU of the non-Sanyo design, it is usually
> harder to upgrade than a TWGS.  That's because
> 7Mhz Zips came with slow cache RAM chips.
> So on older 7Mhz units, the cache RAM chips
> often needed to be replaced.  This is difficult
> because fast cache chips are now available only
> in the 300 mil packages.  Zip GS uses 600 mil
> ones.  Thus adapter sockets must be used.
> These are rather expensive ($7 each).  It is
> either that or solder a new row of socket pins
> for each cache RAM chip to plug into.