Progress is slow, but the project is not dead!
I just have very little time in the past months because of a little addition to our family.
This project requires me to be able to work on it for periods of several hours straight and that's just not happening right now.
I did come to the realization that the pin headers that I'm using to interconnect all the PCB were not sufficient; it did not have enough pins.
That forced me to redo some of the work I had previously done on the circuit designs.
There are now two 64-pin headers in place which should be enough.
Just to be sure I will not do any PCB design until all the circuit schematics are done.
To be continued some day...