Hi ! This is a little off-topic, but what actually prevents from using the 4 buttons of a db9 (regular Megadrive for instance) joystick ? Of course, USB gamepads are more relevant these days, but this would enable to build controllers with no electronic part for instance (arcade cabinets...) and use them in all cores. And use those old Megadrive/Genesis gamepads directly in the MiST with enough buttons for the NES/PCE. Well, that's not really important, just asking. As ATM I use a db9 cable to directly wire my arcade buttons but this only supports two buttons, then. It's simpler and less bound to have defects than making a hack with some cheap USB gamepads.
Just asking, that's not really important
(also, I wonder if CD32 gamepads could potentially work ? even if again, that's not really the purpose of the MiST as all those old controllers will eventually die)