Well I started playing around with the MM78. I got it doing something but doesn't seem to be terribly useful yet. I have it in test mode and am feeding a binary counter into the 8 inputs which causes some of the bits to flow through to the RIO1-8 pins. Not all do, just a few do. Might need a decap to get more information on how the test pin works- it might need to be set to an odd voltage like on the 3850's.