Netronics Phoneme generator info

Random find in my local book store's pile of scrap electronics heading for recycling - a Netronics Phoneme speech synthesizer. IC dates all around mid-1982. I just have the board, no case or anything, but it appears to be reasonably self-contained: there's a connector for PSU, a phono which I'm guessing is speaker out, pots for volume and pitch, and a DB-25 connector. The DB-25 only has pins 1,2,3,7 & 20 in the socket, so I'm assuming it's RS-232. Does anyone know anything about these? Assuming it still works (it looks like it just expects 6-9VAC or thereabouts on the PSU connector), is the control protocol documented anywhere? DIP switch settings? (there are 8 on the board, labelled BSY, 3, 2, /C, /C, B, P, C) Looking at the PCB traces, it appears to allow data input by either pin 2 or 3 (dictated by the '2' and '3' DIP switch settings), but there's no data sent out down the serial line, so communication is write-only. I suppose it's possible that I hook up a terminal and (assuming that I have the line parameters right) start typing English, but it's probably not that simple ;) cheers Jules