MicroMac Performer SE Mod

[Trash80toHP_Mini]

In terms of why the Performer runs at 16MHz and not its primary 25MHz design spec would be analogous to the IIsi underclocking by Apple. MicroMac sold three levels of 68000 accelerators with the Performer as the baseline model. IIRC midrange had RAM/VM under Compact Virtual. Top of the line had cache. There's a product lineup/features chart somewhere in MicroMac's legacy product archive. Speaking of which, a few of you should probably mirror/back up that archive for the day it goes internet ephemeral. Such is beyond my ken and kit.

 

[Trash80toHP_Mini]

HEH! Just in case: a New MOTOROLA MC68030RC25B PGA is on the way. [}] Was wondering about the Performer's power draw at 25MHz from either PDS or especially the CPU tap and thinking about jumpering from an available 5V source. Of course that led me back to  .  .  .

<Tangent Alert >

@techknight I just reread my original Performer in Portable thread and your mac portable accelerator thread. Powering the accelerator shouldn't really be a Battery Life or power supply problem at all. A Portable accelerator could run off an AUX power supply tied directly to the power input lug with a circuit to cut the Accelerator and its parasitic AUX supply out whenever the Power Adapter isn't plugged in to hold the "relay." You'd be running off the 68000 whenever the Luggable wouldn't be plugged in to mains? That shouldn't tax the Luggable's delicate doohickies?

Guessing the 68000/INIT couldn't hand control over to an accelerator that's powered down? IIRC my Plus ran just fine with the Performer pulled and the INIT crossed out at boot.

Anyhoo, not for this thread, but a new Portable/Performer feasibility study might be in order. 25MHz Performer with the "GALs" tweaked to sync at 16MHz? If interested, start one up, maybe we can work a few of the kinks out all these years later?

</Tangent Alert >

@Busterswtback to your regularly scheduled testing program: Can't wait for you to try Bolle's C16M jumper bodge. If the performer will run w/o the 68000 that would be ubercool. []

@joethezombie could you upload the product brochure you scanned to PDF way back when? Borken link to the attachment.

 

[Trash80toHP_Mini]

Joe, the PDF link won't display in my browser, but downloading it worked fine. Found the file while winding up my session. Gotta dig up the link from one of the threads above? Anyway here are the pages that count.

Low end Performer and mid-range PerformerPro:



High end MultiSpeed:



From the FPU and three of five GALs running at 25MHz on the Performer, I think that was the design spec. MicroMac toned it down to 16MHz so as not to compete with the PerformerPro and never released a 25MHz Performer just like Apple hobbled the IIsi at 20MHz when its design spec was 25MHz and the 25MHz IIci just wouldn't die.

That's my WAG and I'm sticking to it! :approve:

 

[Trash80toHP_Mini]

Didn't get far tonight, but I confirmed that my Clocks Diagram with lines for 8MHz connected to 68000 CLK in Red and lines for 25MHz? in Blue was just that, a question to be run down. They aren't, the only thing connected directly to the 25MHz Crystal I have found so far is the asynchronous 68882. HUGE booboo in that diagram is that I have the 16MHz line to the 68030 originating at U5, it's U6. [:I]

What I found tonight and you have in your diagram above in green makes U6 a very interesting nexus for clocks indeed.

U6 Pin  2  is connected to U7 pin 13 and PDS C16M with no direct connection to 68030 E1 CLK

U6 Pin 19 outputs 16MHz to 68030 E1 CLK     (on the 16MHz Performer)

U6 Pin 18 is connected to U4 Pin 1 I/CLK driving it at an unknown frequency

U6 Input Pin 6 is connected to U3 I/O/Q Pin 18 which is interesting because Pin 1 I/CLK of U3 remains a mystery.

I/CLK on U7 remain a mystery as well. If it's only used for generating 16MHz from an 8MHz 68000 CLK pin, would U7 need a Clock Input on Pin 1?