The PS and PS2 use a modified full duplex serial port with a 250 kHz clock signal for the controllers. The Gamecube uses a modified N64 half-duplex serial interface, right down to the 3.8 us timing.

We used to play Wii titles like Super Mash Bros. Brawl and Mario Kart Wii with the GameCube controller, but the Wii U doesn't have the right ports to plug it in. And the Wii U's Pro Controller may ...