[anonova]

Even sneakier, the TI-89, 92, and V200 have a full-fledged Gameboy emulator [1]. It's pretty amazing.

[1]: http://www.ticalc.org/archives/files/fileinfo/369/36950.html

[voltagex_]

Which one would you recommend if I want to develop, rather than calculate?

[acjohnson55]

I would pick the latest TI-84 model. Z80 assembly is significantly simpler than 68k, and the hardware is simpler too. And as you can see, you can still get some pretty incredible results.