PSPTI99 is a port on PSP of the version 0.1.0 of TI99Sim. TI99Sim is a very good emulator of Thomson TI99 home computer running on Windows and Unix. The emulator faithfully imitates the TI99/4 model.

http://dcemu.co.uk/pspti99-a-ti-99-4-emulator-for-psp-v1-0-1-80971.html