I wrote a 15K library of functions on my TI-85 that I used in all sorts of games. It had everything from a text writing program with scrolling, a menu generator that you could select from, a yes-no question app, a really crappy mouse program (you could put up buttons and move the mouse over the button, press enter, and it would return what region you clicked), and a really crappy 3D drawing program that could save 3D drawings that you made.Then, one day, it was gone. Didn't really do anything, just disappeared when the battery got dislodged, or something. I was upset as I had made no backups. Oh, well. I learned a ton about programming from that little labor of love. I guess it's never truly gone. *sniff*
