How to test memory in an HP48 RAM card

[mfleming]

(06-13-2019 08:51 PM)BruceH Wrote:  What did you use for the actual board? Is the edge connector a standard size?

I used a 0.8 mm PCB (that's 1/32" in American) and attached a 0.8 mm plastic strip on the other side from the edge connector contacts to get a snug fit in the connector. Two reasons for the undersized PCB; I had originally planned to build up a case from layers of 0.8 mm sheet, and because the PCB maker charged quite a bit more for the non-standard 1.6 mm thick board. I dropped the idea of a built up case since once the card is in a calculator it usually stays there, so who cares what it looks like?

The edge connector contacts are spaced 0.05" apart, but I didn't find a connector that matched on Mouser. I didn't really try anywhere else, so I can't say if it's standard or not. I've spent the last few weeks validating the cards to make sure there's no design flaw that can lead to premature battery exhaustion or calculator problems. I'll provide schematics and Gerber files once I'm sure I won't embarrass myself

HTH,
~Mark