I started a rough layout of the prototype board by printing and cutting out small squares of paper corresponding to each IC and arranging them. I tried to minimize the distance between the chips that interconnect. This gave me the approximate board size needed. I will probably adjust it when I get the proto board as I'm not sure yet if I will put some of the discrete components like pullup resistors on wirewrap sockets or directly on the board.
A 64-pin wirewrap socket is hard to come by, and the lead spacing varies between the different versions of the 68000 chip (e.g. plastic versus ceramic packages). I made a 64-pin wirewrap socket by cutting two 40 pins units with a hack saw.
These are the controls that are planned go on the front of the board:
- step pushbutton
- single step/run toggle switch
- reset button
- reset/halt LED (red)
- power LED (green)
- power toggle switch
I may eventually put the board in a case. If so, I'll either find a commercial case large enough, or maybe 3D print it.