ti99sim is an emulation of the 99/4a for Linux operating system.
Just unpack the tar-gz - no installation. Note that this is not a licensed package and does not contain any TI roms which you must locate yourself.
Somewhat sensitive to the console grom format but certainly doable.
Main grom files must be called ti-disk.ctg and TI-994A.ctg - note the upper/lower case which is important here.
My Linux command line to launch the sim is:
/windoze/dos3/TI/ti99sim-0.0.10/ti99sim-sdl --dsk1=exbas2.dsk sxba.ctg
which sets which dsk file to use and which cartridge (Super Extended Basic in this instance).