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New CPU Accelerator options for 68K Macs?

Frobozz

Active member
There's a Total Systems 68030 accelerator for the Plus up right now on eBay:

https://www.ebay.com/itm/Mac-Plus-Logic-Board-w-Quesse-68030-Accelerator-incl-68882/333855393411

Doesn't say how much RAM is installed, and it looks like the Mercury version, which I believe is only 16mhz. is it like fantastically hard work to reverse engineer/copy one of these? I've seen the 040 reproduction for the SE (if I remember right) here. Hardware is a mystery to me. If I touch it, I'm pretty much guaranteed the magic will leak out. 

 

Kai Robinson

Well-known member
The PCB itself - no. 

The GAL's on the board? Yes, unless you're lucky and they're 16V8's in combinatorial logic mode. Else you'll have to deconstruct the GAL logic using a logic analyser. 

 

Bolle

Well-known member
This is the 16MHz Mercury indeed. It is limited to 4MB of RAM on the accelerator.

I happen to have the schematics and GAL codes for both the accelerator itself as well as the RAM extension board.

Never got around to actually build any clones of it yet though. Working on another SE 030 accelerator right now that will support 16MB RAM and go up to 50MHz (and has video output as well)

I felt like the entry level Mercury wouldn’t be worth the trouble...

 

maceffects

Well-known member
That project might render the Brainstorm clone project I’m working on a bit inferior. However, I’m sure I’d buy one. I’d still love to get my hands on one of your socketed SE/30 upgrades if you ever do it again. 

 

mg.man

Well-known member
it looks like the Mercury version


It certainly says Mercury 030 Plus on the 'board... but the one I have is for the SE as well, and has a PDS connector.  No sign of that on this one...

This is the 16MHz Mercury indeed.


Are you sure?  The oscillator is 20Mhz... that memory expansion does look like a later one... v1.2... How many flavors of these did they actually make?  Are there any ex-Total Systems ppl still kicking around?

 

Bolle

Well-known member
Are you sure?  The oscillator is 20Mhz
The oscillator is only connected to the FPU. The CPU is hardwired for 16MHz.

that memory expansion does look like a later one... v1.2... How many flavors of these did they actually make?
According to a product catalog from back then which I saw somewhere on archive.org the Mercury never did more than 4MB.

While we're at it: View attachment Total Systems Mercury.zip

Totally not tested and schematics have not been cleaned up for readability. Most parts values missing, you'll have to source those from the pictures.

GAL files are however correct and tested.

 

mg.man

Well-known member
The CPU is hardwired for 16MHz.


Good to know...

Speaking of while we're at it... I recently acquired a Gemini 030 in a sad state... it's configured for an SE, but it doesn't appear to be working... all I get when powering up is this... no "bong", no pointer... :-(

20210113_003420.jpg

I suspect it's because one of the GAL? chips is missing [U4, upper left] (but really have no idea)...

20210113_104204.jpg

Open to any suggestions or happy to send to you if you want / have time to take a look... Does the file you attached include GAL details for the Gemini?

 

Bolle

Well-known member
Does the file you attached include GAL details for the Gemini?
Nope, those files won't help you there.

If the GAL in that open spot is indeed needed I'd say there's not much I can do for you without another one of those which has the needed GAL in place to make a copy.

Seeing you've got the power connector on there though makes me wonder if you need a secondary power supply hooked up to get it to work at all.

Can you meter out if the VCC pins on the PDS connector are even connected to any components on the accelerator? On the Mercury there are several jumpers to select different power sources...

In the SE it would be obvious to have everything powered through the PDS connector. On the Plus you can choose to get power through the 68000 clip or an external power supply.

It's the same with Quik30 I got in my Classic which needs a secondary power supply to work at all as there is no power supplied to the accelerator through the clip that goes onto the logicboard CPU.

 

mg.man

Well-known member
Nope, those files won't help you there.


Yeah... I d/l'd and saw they were Mercury-specific... drat!

not much I can do for you without another one


Feared that as well... I know a couple of MLA'rs have one of these... but set up for a Plus - the ones I've seen do have a chip at U4.  :-(   My only hope is that it's only required in "Plus" mode... but that's likely a wild hope...

makes me wonder if you need a secondary power supply hooked up to get it to work at all.


Yeah... I've been wondering that too... I'll see if I can do some probing...

Thanks for the info / suggestions!

 
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mg.man

Well-known member
Doesn't look like it's a VCC issue... compared this 'board to my [working] Mercury 030 and the +5V pins from the PDS are carried onto the 'board.  In fact, they are connected to the two right-most pins of the power connector...  :-(

 
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