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ROM Pinout in Wiki

trag

Well-known member
I have added the 160 pin PPC ROM module pinout to the Wiki. If anyone wants to go clean up the formatting I'd appreciate it. I'm not so good with that stuff. I mostly just cut and pasted the document I have here:

http://www.io.com/~trag/Apple_pinouts/Firmware_Module_Pinout.txt

into the page.

Also, I have the PCI PPC CPU module pinout and most of the Bandit chip pinout at the same location, in case anyone wants to download the files and add them to the Wiki under an appropriate heading as well.

One interesting note about the CPU module pinout, there are three pins labeled CLKID[]. Apple used these three pins to encode the speed range of the CPU card so that the logic board could automatically adjust its timing parameters before booting.

There are many CPU upgrade cards which just won't do a bus speed higher than 45 MHz. and in most cases this is probably because of the CLKID pins on those CPU cards.

The fastest (bus speed) CPU upgrade card I had was a Powerlogix something or other with adjustable speed. What I found was that they put a tiny microcontroller on there which changed the CLKID pins as one adjusted the bus speed of the card. On that card, I could get 62 MHz bus speeds on most power surge (x500) machines in which I tested it.

 
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