The 3DO Control Pad, or FZ-JP1X in this case, is a rather interesting device. It’s built around a central gate array chip, the TC11L003 chip, consisting of 300 gates.
The way these chips were “programmed” was by changing the metal wiring connecting the gates.
It would be very interesting to have a peek at this chip under a microscope, but I’m not willing to sacrifice my only 3DO controller.
Interestingly, the chip in my particular controller is Matushita branded, though the chip was designed by Toshiba.
The controller PCB is branded Mitsumi Elec. Co., LTD., while the controller itself claims to be made by Matsushita Electric Industrial Co., LTD.