The NTT Data Keypad is a essentially just a souped-up SNES controller with 15 extra buttons (and a single flipped bit), which would be incredibly easy to implement, it is used on the defunct JRA PAT horse-betting program, and homebrew games that support it.
The NTT Data Keypad is a essentially just a souped-up SNES controller with 15 extra buttons (and a single flipped bit), which would be incredibly easy to implement, it is used on the defunct JRA PAT horse-betting program, and homebrew games that support it.
https://www.raphnet.net/divers/ntt_data_sfc_controller/index_en.php