Reading old HP-65 program cards

[[kby]]

If you mean what instructions the 6-bit opcodes decode into, that information is in old 65-notes issues. There is, as you noticed, no header.

However, I would only try this technique as a last resort if the cards won’t read. First, I’m not sure it’s non-destructive. Second, if the card can’t read in the calculator,it likely won’t have enough to read visually either. There is minimal error checking (many parity? It’s documented but I don’t remember offhand), so a card is more like to misread rather than get an error, I think. Generally I have found cards mostly read, both ones I’ve made and the commercial ones from HP. The usual culprit if they look ok is magnetic fields; it doesn’t seem to take much to demagnetize them.

I have had one 65 that I was certain had not been opened that had a good card reader in it and its roller did not look like the usual polyurethane one; I recall it being black. I have no idea why that one was unique.

I’d certainly volunteer to try to read them on one of my -65s. I don’t have any magna-see, iron filings, or trichloroethylene.-kby

(03-02-2021 11:53 PM)Gene Dorr Wrote:  That's certainly helpful. It looks like there's no header at all, just the raw program memory. Any clue where I might find the decoding of the 6-bit values beyond what is shown in the example?