Apple Attachment Unit Interface - Connector and Signals

Connector and Signals

AUI used a full-sized 15-pin D connector (model DA-15) that used a sliding clip for mechanical connections in place of thumbscrews. AAUI replaced these with a small 14-position, 0.050-inch-spaced ribbon contact connector. The connector may have been changed to avoid confusion with the monitor port on early Macintoshes, which also used a 15-pin D connector. The connector was locked into position using two clips or hooks on the sides of the connector outside of the D shell (where screws often are on D subs) which automatically clicked on when plugged in, and could be removed simply by pulling back on a sliding sheath over the body of the connector, disengaging the hooks. 3rd party AAUI devices often omitted 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 volt 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.