The original design was rather painful to work with, and ugly, so I put this together which is a little nicer. The button, switch, chip socket, and cable socket are one ElectroCookie Snappable PCB. I like those PCBs as they have three-hole strips.
I found some decent sockets that fit the old chips (2732A and 2764 EPROMs). In retrospect, I maybe should have got a zero-insertion force sockets where you just drop the chip in and pull the lever to tighten.
With this setup, I can have one ribbon cable going from this board to the Mega. I didn’t know what kind of cable or cable-connectors I needed to fit this 36 pin setup, so I made a cable using the commonplace loose-end Arduino ribbon cable. The pins bend rather easily, but it is better than the previous setup.
I’m still using magnet wire – for which I’ve developed a love/hate relationship. The magnet wire looks nice, is easy to cut, and one roll lasts pretty much forever. But it is rather a pain because (1) you have to boil the coating off the ends of each piece of wire with solder before you use it, and (2) you have to put a blob off solder in the hole first and then reheat it to stick the magnet wire in. Regular insulated wire, that is sized correctly for the hole, is sounding very appealing at this point. But, it works.
Something fun I learned in the process: I wrote a Forth script for testing the pin connections. The output of the script comes from Mega over UART (serial), but I used vte style escape codes to keep the display fixed and updated on one part of the terminal screen.