TI99Sim is a very good emulator of Texas Instruments TI99 home computer
running on Windows and Unix. The emulator faithfully imitates the TI99/4 model
(see http://www.mrousseau.org/programs/ti99sim/)
Dingux-TI99 is a port on Dingoo/Dingux of the version i've previously ported to Wiz.
How to use it ? Everything is in the README.txt file.