Hardware/Expansion Interface

EXI (EXternal Interface) is an SPI-like bus. On the GameCube, it is exposed via the Serial Ports and Memory Card slots, and is used internally for the IPL ROM, as well as the RTC. On the Wii, it is exposed via the Memory Card slots, and used internally for a stripped down GameCube IPL, as well as the RTC. The Wii Family Edition and Wii Mini are identical in this regard, but don't have the actual memory card slots (the traces for them exist though). The Wii U technically also has it, internally only.