Gave up on it
For Reproduction Solid State Music IO-2 S-100 Board
The board is not bad although some of the traces are very, very close to each other. The problem is the SSM documentation which consist of a bunch of hand-scratched notes and a few clips from data books. It's more of an experimenter's board. For a serial interface, most of the traces are missing, and wire-wrapping or soldering the connections quickly gets to be a mess. In the end, however, it was the lousy vintage documentation that killed it for me.
