I learned to program in BASIC on a Tandy 1000SX and an m100. That thing was great for long trips to grandma's.
I still remember my very first attempt. I tried typing lines from a BASIC book into a DOS prompt, which obviously frustrated my tiny being to no end. My dad showed me how to start gwbasic, and I've been on this ride ever since.
http://en.wikipedia.org/wiki/TRS-80_Color_Computer