128kb Plessey DG Nova 3 Memory Board

Bit 9 cannot be set after the machine has been running for 5 minutes or more. Clearly a thermal problem. Without the board schematics I will have to trace the MEM9 signal from the card edge connector inwards. Schematics would have been great! If you have the schematics for this board, a copy would be much appreciated.

The bit 9 error is now fixed; it was a faulty SN74S373 latch on the memory bus.