Cards with word and phrases (NNNs) for HP-67/HP-97

[teenix]

Quote:I am also curious about how it can destroy the printer.

Quote:By leaving the printhead's thermal elements on for far too long. They first burn the thermal paper to a crisp, then immolate themselves.

The PIK chip (afaik) only accepts 4 or 6 bit print data depending on the command sent to it. There are only two types of print command sent to the PIK from the 97 even though a few more are available, either way they are all interpreted as a maximum of 6 bits inside the PIK.

There is no way that sending the data from the C register should kill the print head as it will be internally formatted to 6 bits as an index for the 64 character ROM table lookup. I originally thought the table overflowed with dodgy data, but thinking more, that should not happen.

I'm not 100% sure but the only thing I can think of with these NNN's being sent to the printer is that somehow there is no End Of Line character send in the data stream and some uncontrolled loop starts inside the PIK chip which keeps the heads on too long. HP mentioned that this character MUST always be sent to the PIK as part of a print line. The other thing that might happen is the print carriage jams hard against the opposite side of the printer frame and stalls the motor causing other damage like stripping the soft idler gear.

If I had one of these NNN numbers, I could inject it into the emulator and see what happens when it is processed by the HP print code.

cheers

Tony