strange HP-97A

[Katie Wasserman]

(08-06-2016 05:44 PM)BobVA Wrote:  So it appears to be able to write (and presumably read?) keystrokes. The subset of LED segments selected is still puzzling, though.

Cool find! Bob, I completely agree with your analysis.

The subset of the segments are almost exactly what's needed to determine the number displayed using just 4-bits, with one exception. I don't see how the numbers '6' and '8' can be distinguished. It's possible that the service manual schematic is wrong and it has the labels for segment B and segment F reversed. If so, then this is exactly the 4 bits needed to decode the decimal digit and with a bit of logic one could not only simulate the pressing of the keys but also read the number on the display all through the 14 pin connector.

So this 97A was likely used as a calculation engine. It would be very interesting to know what was hooked up to it.