Ditto on the TI-99/4a!..and much the same experience as the OP...writing small programs to solve algebra and physics problems. I even bought the Extended Basic cartridge but the cassette interface went out, and I never really got to use it. I still have the console, joysticks, and all the cartridges. I assume it would still work if I plugged it up. Does anyone remember the Scott Adams Adventure games? 🙂