abbeyj

I think if you try to do this on an unmodified Genesis controller you'll run into the problem that only Up and Down will work. The rest of the switches go through the mux chip in the controller and that won't work without 5v power on pin 5. You can modify the controller to bypass the chip and connect the switches directly instead. http://smalltimer.net/dlormand/segactrl.htmlhas instructions for doing this to produce an Atari-style pinout. You could follow those instructions and then try switching the pinout on the cable around to match the TI-99.

I've used this Belkin cable with a USB-to-serial converter to connect to my PC. Its just a plain 9 to 25 cable (NOT a null modem cable).