I did subsequently find better quality scans of the schematics (Attached) but need to have a proper look, but they still don't seem to show the two expansion connectors, which seems a bit odd.stephen_usher wrote: Tue Sep 22, 2026 6:40 pm I seem to remember finding a schematic on-line
I’ve seen far noisier lines and the noise doesn’t go near TTL switch voltages. Then again, the SRAM may be more sensitive.
The schematics do show a 4164 based internal RAM expansion, but again, no connectors shown, just an extension of the address, data and control signals from the main schematic.
I've seen noisier too, so I'm not convinced that's it either. Pretty weird though. I'd assume from looking at the schematics that if Nick and Dave were bad it would be unlikely that anything was working.
Will look again later in the week but I'm in London tomorrow, so won't be for a day or two.