HP-67 DSP vs FIX

[brouhaha]

(12-01-2023 03:02 PM)John Garza (3665) Wrote:  [didn't the 67/97 use some of those unused codes for the famous Word/Phrase/Graphics ?

The display phrases were the use of non-normalzed numbers (NNNs) to get the letters C, E, d, o, and r in the displays by having hexadecimal digits A-E (and F for a blank) in a number. That by itself didn't directly use or require the extra 6 instruction codes. However, one way to get the NNNs was to glitch the calculator, using a phase 1 clock interrupt switch, or powering it through a rheostat, such that program lines could be read as data registers. Then the extra 6 codes could sometimes be useful.

On an HP-67, but not the HP-97, there were key sequences using multiple simultaneous key presses,which could insert the extra 6 scores into program steps.

WARNING: If you mess around with NNNs on an HP-97, have the printer mode set to MAN, and do not execute any printer functions. Printing NNNs can cause the PIK chip to hang with printhead drive lines active, which burs up the printhead very quickly.