What is (or was) gc_n64_usb? gc_n64_usb if a firmware for Atmel AVR micro-controllers which allows one to connect an Nintendo 64 or Gamecube controller to a PC with an USB port. The joystick is ...

The Nintendo 64 controller is powered at 3.3V using a linear regulator. The N64 controller data line is connected to PORTB0 (open collector output). The USB D+ and D- lines (connected to PORTD2/INT0 ...

As gaming consoles age the controllers will inevitably ... a similar hack using an AVR. Both convert the signals into the rotary encoder format that the N64 chip is listening for.