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New CPU Accelerator options for 68K Macs?


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2 hours ago, mg.man said:

Are you sure?  The oscillator is 20Mhz

The oscillator is only connected to the FPU. The CPU is hardwired for 16MHz.

 

2 hours ago, mg.man said:

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: 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.

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2 hours ago, Bolle said:

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.thumb.jpg.b07cf4e48b2d439f72b1571439f85119.jpg

 

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

 

20210113_104204.thumb.jpg.34529d13f0a95aec195cee073250f072.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?

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2 hours ago, mg.man said:

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.

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2 hours ago, Bolle said:

Nope, those files won't help you there.

 

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

 

2 hours ago, Bolle said:

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...

 

2 hours ago, Bolle said:

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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