We have a winner. :)
I learned originally on a VIC-20 by typing in games out of books from the public library. At some point we upgraded to an XT and a friend sold me a copy of Power C for $20. It came with a beautiful hard copy library reference and the rest, as they say, is history!
Check this out for a trip down memory lane: http://www.mixsoftware.com/product/powerc.htm
Yeah, the graphics library was great! When I moved on to Linux and gcc, I was disappointed for a while that I didn't have all those super simple primitives to work with.