The TI-89 blew my mind when I accidentally discovered Exact Mode. I had fed it a problem from my Number Theory homework just for fun... it wasn't supposed to actually answer it!
This takes me back. In high school I actually modded my TI-89 (circa 2001) with a lower Ohm resistor. The clock ran on a simple RC circuit, so you could "overclock" it by soldering in a new resister. Got a pretty impressive bump as I recall. And then when it became common enough games started to support a turbo mode!
