A general-purpose input/output is an uncommitted digital signal pin on an integrated circuit or electronic circuit (e.g. MCUs/MPUs) board which may be used as an input or output, or both, and is controllable by software.

Management Data Input/Output, also known as Serial Management Interface or Media Independent Interface Management , is a serial bus defined for the Ethernet family of IEEE 802.3 standards for the Media Independent Interface, or MII.