Now heres a very strange one. I finally got around to cracking open my Akai S20 and located the RAM chips (which are a pair of HM514260CJ's), and with the help of the datasheet got some excellent stuff going on by shorting the address and I/O pins together as per usual.
Looking at the thing i concluded that theres no way to mount anything on the case so i cut a hole in the back, mounted a 25 pin socket and then wired all the useful pins to the socket for an external patchbay. Unfortunately as soon as i plugged in the connection cable the s20 suddenly started acting like every single one of the pins was connected together, even though there was nothing on the end of the cable. I've tried a few different cables and can only conclude that the individual wires are acting like aerials and somehow interacting with each other inside the cable.
What makes this even stranger is that a lot of the RAM chip pins, specifically the I/O pins, have no effect when shorted together with a wire longer than 5 or 6 inches, but with a wire of about 2 or 3 inches there is a minor effect, and when shorted with a half inch piece of bent jumper wire there is a full on effect. It seems like the resistance of the length of wire is actually cutting the level of the effect somehow!
Has anyone got any explaination for what is going on here as it seems completely inexplicable to me. It actually looks like i'm going to have to give up on the external patchbay idea and just mount a few switches as close to the RAM chips as possible just to get them to work!