Apple Attachment Unit Interface

thumb|right|300px|AAUI transceiver for [[10BASE2 with cable]]

thumb|right|300px|AAUI transceiver for [[10BASE-T]]

thumb|right|300px|Two AAUI 10BASE2/10BASE-T combo transceivers (Linksys MACT2T and LL8-LEENET-C) and an AAUI dual 10BASE-T transceiver that is actually a three-port hub (Farallon)

Apple Attachment Unit Interface (AAUI) is a mechanical re-design by Apple of the standard Attachment Unit Interface (AUI) used to connect computer equipment to Ethernet. The AUI was popular in the era before the dominance of 10BASE-T networking that started in the early 1990s; the AAUI was an attempt to make the connector much smaller and more user friendly, though the proprietary nature of the interface was also criticized. The connector locks into position using two clips or hooks on the sides of the connector outside of the shell which automatically clicks on when plugged in, and can be removed by pulling back on a sliding sheath over the body of the connector, disengaging the hooks. Third-party AAUI devices often omit this sheath, requiring the user to directly squeeze small tabs on the sides of the plug housing to detach the hooks.

AAUI signals have the same description, function, and electrical requirements as the Attachment Unit Interface (AUI) signals of the same name, as detailed in IEEE 802.3-1990 CSMA/CD Standard, section 7, with the exception that most hosts provide only 5 volts of power rather than the 12 volts required for most AUI transceivers. An adapter containing a power supply to provide the required 12 volts was available from Apple to permit connection of standard AUI transceivers to an AAUI port. This facilitated direct connection to 10BASE-F (fibre optic) and 10BASE5 (ThickNet) Ethernet networks, for which AAUI transceivers were not available.

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