After having further studied the available documentation and having played aorund with a preliminary board design in KiCad, I have decided to revise the design a bit.

Since I will need to have the PCB fabricated (no breadboard PCB this time), I have settled for a eurocard sized (160x100mm) board with two layers to keep the cost at a reasonable level. Since there is not enough space on such a board for the amount of RAM I will eventually need, I have decided to dial things back a bit for the first part of the project.

Second, the 32 bit RAM banks and their associated selection, decoding and bus cycle termination signals is still something I am in the process of getting my head around.

So for now, I am aiming for a simpler design with just 512 KB flash and 512 KB RAM using an 8 bit data bus. If I can manage to get that to work I can implement more advanced stuff on a second board later on.

I have also decided to use the multifunction peripheral MC68901 which I have found in a PLCC package instead of the 68681/68230 combo in order to save space and limit complexity of the board.