Calculator

I wrote many programs on this old calculator. I wrote a chess program, and a race-car game. I wrote a maze game that used data compression to fit many levels in the small memory, and another that made infinite random but still solvable mazes. For chemistry class, I wrote a program that could "roll" virtual dice, instead of the real ones, for an experiment on nuclear decay. After seeing a tv show about the enigma code the Germans used in World War Two, I wrote an encryption program that was based on it, but more powerful (many decades of technology made it much easier for me to do than it would have been for them).

On my way to visit my then girlfriend in Europe, I wrote a game program for her that had a hidden, and encrypted, love note built into it. I put the program on her calculator and later, an ocean away, I surprised her with how to get it to ask her for the secret code and to read it. A few of my math grades may have reflected the attention I gave this device, instead of my school work. But I had a lot of fun, and still use much of what it taught me.