This is a 68040 to 68060 adapter. It allows you to physically connect a 68060 CPU to any CPU socket that fits a 68040 CPU, assuming there is enough physical clearance.
This work is a derivative of the 68040 to 68060 adapter by richx which in turn is based on a 2013 design from the a1k.org forum.
At the time of this writing, the original kicad project can be found at https://eab.abime.net/showthread.php?t=100942
The differences between this design and the original KiCAD version are:
- Moved the inner 4-pin connector in line with the substrate and the pins of the PGA socket. This allows to use sockets with 5 rows of pins without using a dremel.
- Move the capacitors a bit more to the center to make space for 5 pin row sockets.
- use 0603 4.7k resistor networks instead of 0805 resistors to clean up the space and have fewer parts to solder
- move all three diodes in line for easier soldering
The two PCBs need to be separated before assembly.
It is possible to build these with 0.1" pitch breakaway female pin headers. However, is is much easier to solder full PGA sockets. The top one has 206 pins, the bottom one 179. That is a large number of breakaway pins if you go down that route.
'NOTE:' The bottom of the top PCBs has circles around some of the pins. These are carrying VCC and must not make contact to the bottom PCB or you will operate your 68060 at 5V instead of 3.3V. You might destroy your processor this way, so be careful.
During assembly, you have the choice to either cut those pins, or you can use an intermediate socket with those pins removed. This will increase the height of your adapter by a few mm and increase the price because you will need a third PGA socket, but make the assembly process a lot cleaner and more reproducible.
Further reading on my adventures building these:
Here's the Bill of Materials (BOM).
Big thank you goes to richx, who did the original KiCAD version and to Mozart, Lemmy and Matze from the a1k.org forum for the Eagle version before that.