Atari 800, with a whopping 64k. My father used it to telephone into the work mainframe. I used it to play games. Eventually, BASIC became one of the more interesting games I played. :) Still have the casettes with my first programs someplace.

The school had a few trs-80's, and I would get yelled at for making them do things my teacher couldn't grade because it was in excess of the assignment.