I have a few small ideas on some boards I'd like to design for the TI-99/4A. Something simple at first while I learn TMS9900 assembly.
One such idea is to build a board to convert the NES controller to something the TI could read. I know the NES uses a serial shift register and the TI (or something) would have to supply a clock, etc. to get the values out of the NES controller.
I don't see a way for the TI to send an output pulse through the joystick controller. So my initial thought would be to connect a small ATTiny to the NES controller and constantly read the controller at maybe 30-60 times per second.
Then, the micro-controller could send the parallel value to the joystick port. However, I didn't see anything in the pinout that could support this.
I would need 4 signals for the directions and 4 for the buttons (A,B, Select, Start). The TI only supports one fire that I saw.
Then I thought...what if I wrote a serial driver for the TI and just monitored the trigger button? Then serialize the NES controller stream over that.
I would need some clever way to sync the devices, however.
What are your thoughts?
With 32K of RAM, an F18A (and a possible soundcard I want to build), the TI is shaping up to be a killer gaming system that deserves a good controller.
BTW, I love the Genesis controller and perhaps it would be easier...but I'm after the NES controller.