That was a phenomenal write-up of what must have been a fascinating mystery to have discovered! Thank you for sharing it with us!
As an aside, would you mind sharing your list of edge cases? I have a few for scientific calculators but nothing for financials. If one doesn’t already exist, maybe we could even start working on a community document with edge cases and benchmarks?
You got written up in The Register! That is amazing, wonderful, and awesome! Congratulations! https://www.theregister.com/2024/09/21/hp_12c_calculator_mystery