HP-67/97 special "synthetic" cards

I have heard rumors of special cards that enables some tricks on the HP-67 or 97. Anyone here having access to these cards and can send me a set of copies?


I don't have any of those cards, sorry.

A word of warning, though. Don't ever try to print "non-normalized numbers" (NNNs) on the 97. On some 97s, printing a number containing a hexadecimal "F" digit can cause the PIK chip which controls the printer to leave some of the drivers turned on, which burns out the printhead in a few seconds. If you ignore the warning and try to print NNNs anyhow, if you smell smoke or notice any other funny behavior from the printer, turn off the calculator IMMEDIATELY, and you *might* save the printhead. There is unfortunately no source for replacement printheads other than cannibalizing other Topcat series calculators.

Whether a given 97 has this problem apparently depends on whether the PIK chip was made by Mostek or AMI, but I'm not sure which is which. I wouldn't risk it on any 97.

On the 67 it is safe to play with NNNs. Aside from amusing displays, it isn't very practical.

The 67/97 have six undefined instruction codes. On the 67 it is possible to enter some from the keyboard using key sequences with simultaneous presses of two keys. On the 97 this is not possible, because the PIK chip has a hardwired keyboard encoder that rejects phantom keys. In any case, the six undefined instruction codes all execute as NOPs on both the 67 and 97.


I have been thinking about building a printer interface card that would allow the use of 82143A printers in the HP97, etc. It would need a DC-DC converter and a microcontroller to adapt the different speeds of the print mechanisms.

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