I became good friends with the salesmen (yes they were all men back then) and they liked me working in the window...it helped them sell the system if they could show a 12-year old kid writing programs on it. "How hard can it be if..."
The first real program I ever wrote was in MS ROM-BASIC (that's what I remember calling it, because it booted into it if you didn't put the DOS floppy into one of the two (yes two, we were lucky!) 360k floppy drives it had.
The program was a blackjack simulation and trainer for counting cards. My older brother became infatuated with the topic and I remember reading the books on it and wondering if the math and systems were real or just casino trickery.
So I learned this version of BASIC and went to town, building decks of cards and configurable card-counting systems, and proved to myself that, yes, under certain conditions, BJ counters do actually have a long-term advantage over the house.
It's fascinating to see the actual code that ran my simulations.