Apple IIgs - overclocking possible?

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I recently scored a used Apple IIgs ROM-1 and while I am waiting for it to arrive, I'm learning about what this machine actually is.

From wikipedia:

The use of a 2.8 MHz clock was a marketing decision intended to limit the IIGS's performance to a level lower than that of the Macintosh, a decision that had a critical effect on the IIGS's success;[2] the 65C816 processor is capable of running at a much higher clock rate.

So has anyone figured out if it's possible to actually get a better / faster clock or performance into one of these?

I have also happily learned that much of the Apple II software line is backwards compatible, and it's got me thinking that I would like to try and get back into programming on this machine. I have two Apple IIe machines (one original, one enhanced) and maybe it's the holidays, but I'm feeling darned nostalgic these days, and feel a need to get into some BASIC commands of my youth!!

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Re: Apple IIgs - overclocking possible?

Unfortunately so far as I'm aware there's no published recipe out there for a simple-to-pull-off DIY method of increasing the speed of a IIgs. There are accelerator cards, such as the Transwarp GS and Zip GSX, but they're quite complex and include things like cache RAM to enable the CPU to run asynchronously from the motherboard. With one of those cards it's possible to push the IIgs up north of 8mhz but they tend to go for a pretty penny on eBay. (If you're *lucky* you might snag one starting at around $400, but $600 is more typical.)

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Re: Apple IIgs - overclocking possible?

Ugh, that hardly seems worth it.

I'll check local garage sales in 2017 with fingers crossed.

I am presuming that there wasn't much call for overclocking back then? It doesn't seem like Apple really wanted people to be able to easily do it (since they'd be pushing the Mac, and lots of other enhancements were much simpler), but I'm surprised that there weren't more options created to do this, unless nobody cared that much.

Apple obviously knew it could be done.

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Re: Apple IIgs - overclocking possible?
gsmcten's picture
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Re: Apple IIgs - overclocking possible?

Stats,

To get full back story of the IIgs go here:

http://apple2history.org/

One stop reading for Apple II.

Steven Smile

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Re: Apple IIgs - overclocking possible?

18.75MHz!! Really cookin'!!! That's amazing.

Man, it's too bad they're so rare and expensive.

Thinking back, we really tolerated a slow processor in 1986...but looking back, its glacial speed wasn't even something we noticed. We were just so happy to have a computer to hack on.

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Re: Apple IIgs - overclocking possible?

gsmcten wrote:

Stats,

To get full back story of the IIgs go here:

http://apple2history.org/

One stop reading for Apple II.

Steven Smile

Well, there goes the rest of MY evening! Thanks, Steven!!

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Re: Apple IIgs - overclocking possible?

Hello Statsman1,

just a few technical explenations to limiting the "tuneup" of the mainboard itself:

Apple wanted to compact the mainboard to keep the caseunit as small as possible...
by that they reduced large amounts of TTL logic-chips by instead using so called
"custom made LSI ( Large Scale Integration ) chips..." ( the big square ones on the
mainboard ).....
but this chips ( specially such like the VGC ( Video graphic Chip ) and the HAL
( a small PAL chip (Programmable Array Logic ) )are calculated to a fixed basic
speed-adjustment from a crystal oscillator. If you tune the basic speed at the
mainboard that kind of chips will fail to serve demanded purpose.

So the accelerator cards have been forced to "split" the acceleration:

Running the program itself faster in the faster cache memory of the card at "high-speed"

- while leaving the action of the "peripherial devices" like:

monitor/video output ( VGC )
and communication to interfacecards ( FPI and Mega2 ),
keyboard, mouse (ADB )
serial ports ( at the rear panel )
diskdrives ( WOZchip )
Sound ( Ensonique chip )
and so on at regular
normal speed of the VLSI-chips of the mainboard.

That's also the reason that in the Option panel the unit still offers the
option to run at 1 MHz instead of 2,xx Mhz .... some of the old interfacecards
from the old Apple II system demanded to run at the slower speed of 1 Mhz.

speedyG

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Re: Apple IIgs - overclocking possible?

Thanks, Speedy!

If I understand what you're saying, overclocking (or speeding up) the CPU wasn't really "overclocking" as we know it today - the graphics (as in the 21st century term "frames per second") didn't speed up, only the processing did, provided the program being run was stored in the cache memory of the accelerator card.

So, really, at the time, there wasn't much need to do overclocking unless you were doing some heavy-duty internal processing.

Thanks for the info!!

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Re: Apple IIgs - overclocking possible?

Hello Statsman1,

it seems you only caught half of the truth.....
What i said. was that the LSI chips did not accept "overclocking" in that way
of "common sense" that you change the crystal and thereby speedup the entire system...

But what you missed is this:

You assumed there not much sense in just speeding up the program in cache to be effective....
that's fairly wrong !
Your wrong assumtion is the result that in nowadays systems the graphics are generated in
seperate Graphics processors with own graphics memory..... and that fellows have own clocking....
BUT:
In the Apple up till IIe enhanced there was no real graphics processor ( except if you used
"special graphics interface card" ) and the generation of the graphical data was still
generated in the regular program memory ! Therefor it made quite much sense to speed up
a system with an accelerator card ( specially if you recognize that for graphical data
there is a huge bunch of math operations to be performed ! )
- so at that point accelerator card of course also could speed up graphical display
because graphical data became much faster availiable from the program and then was
tossed over from cache to the memory and at the IIGS the graphical LSI chip was
availiable for display.... but had no "internal processor capacity"

just for the records:
The GVC ( graphic video chip ) in the IIGS was not a processor - it just replaced the
regular bunch of TTL chips that formerly managed to generate that what you call a graphic display....
but without own "math power"..... and at the //e the Video ROM also of course had no "independent
own math power"....

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Re: Apple IIgs - overclocking possible?

OH! Ok, now that makes more sense to me. Thanks, Speedy!!

Now - do you have an easy solution to get a mouse working with a IIgs? Without going to eBay and getting ripped off? Does a USB to PS2 adapter work in a IIgs for a more modern mouse? Or is ADB completely incompatible with PS2 adapters?

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Re: Apple IIgs - overclocking possible?

Sorry but ADB won't work with USB.....
both are serial communication - but the handshaking is very different !
ADB mice are often not only offered at ebay for Apple II series but also for old macintosh series....
and old mac mice usually get accepted by the IIGS...

and usually you just need a bit patience....
it's still not magic to get ADB mice at a price below 25 bucks....

It's rather more a problem to get that devices cleaned up correct
( cleaning inside the LED gates and the interuption wheels as well as the
rolling ball and the takeup rolls.... sometimes it's also recommended
to expand the pressure spring again a bit to get better traction )....
best is the use of isopropanol alcohol ( at least 75% or higher )...

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Re: Apple IIgs - overclocking possible?

The ADB worked the same way in the early Macs AND the IIgs? So something offered up on eBay, like this...

Mac ADB Mouse

...would work?

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Re: Apple IIgs - overclocking possible?

yep...

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