Hi Dave, Thanks for your suggestion. I suspect the floppy is used in a standard way driven by the interface attached to it. As I have never seen it running I cannot record anything on the discs. Alarm 10 comes up most of the time "Disk Write Protected". There is no 5 volt supply to the FDD or to any of the chips on the interface so I suspect that this is the reason it does not work. I have been trying to find a schematic so that I can investigate properly but no luck up to now. It could well be that the CPU board sends signals to turn the 5V rail on. When I can have another go at it I will get my oscilloscope on various pins to see what happens. I have tried once but it didn't tell me a lot. Next time I will use a dual trace scope and see if that helps.
