I'm not sure of the first thing I ever coded, but one of the first things I coded when I was little was a program on the Tandy Color Computer 2 that made discs out of concentric circles in random spots on the screen while playing increasing notes.. for some reason the computer rendered the the circles with colors in them (I imagine it was some kind of subpixel rendering to make them more round), so the disks looked a lot like CDs with their iridescence.