@amoroso hmm, I remember in 1980 helping a friend who had a TI calculator that could be programmed, and could save its programs onto little thin cards.
We wrote a prime number seeker (prove N to be prime then try the next number ad infinitum) but that's all I can remember.
I had to switch my thinking a bit because I'd already been used to my brother's HP-45 - not a programmable but I'd set myself sequences of actions for it (i.e. I was the program).