MIOS is a special version of IOS that runs when the Wii enters GameCube mode. The same MIOS is used for all GameCube games and software. It has seen minimal updates in the Wii's lifetime.
It contains a full copy of the GC IPL, slightly modified for the Wii. It performs patching of some games when they load, presumably to enhance compatibility with problematic titles.
||Present on Prelaunch System Menu consoles.
||Present on Launch Wiis as well as Korean Wiis (which lacked gamecube functionality at launch).
||Blocks the GameCube Action Replay.
||Overwrites memory to prevent the Tweezer Attack.