TI83 emu is a Texas Instruments 83 emulator for the Gameboy Advance by Dwedit.

How to use: Append a TI83 rom image to the end of the .gba file, using something like “copy /b ti83emu.gba + ti83.rom ti83emu_rom.gba”

Keys:
SELECT: Toggle keyboard overlay
Keys (keyboard visible)
* Arrows: Move cursor
* (right now cursor is not displayed over arrow keys, just move it away a few times)
* A: Press that key
* B: Quick Keys
* Start: ENTER
* L: Alpha
* R: 2nd

Quick Keys: (Hold down B while keyboard visible)
* A: ENTER
* Arrow Keys: Arrow Keys
* (other keys same as keyboard visible)

Fullscreen Keys:
* Arrows: Arrows
* A: 2nd
* B: Alpha

If you have problems, you might find an answer here: http://www.dwedit.org/dwedit_board/viewtopic.php?pid=1978