Apple Attachment Unit Interface

The Apple Attachment Unit Interface (AAUI) is Apple Computer's proprietary implementation of the (AUI), an otherwise standard port defined by IEEE to connect a transceiver (or dongle) from the computer's Ethernet hardware to the physical cable of a network.

Design
A standard AUI port uses a connector, which looked like the monitor port being used by beige-era Macs of the time; Apple's AAUI connector is more compact to avoid confusing the two.

History
The AAUI port was first introduced in the Macintosh Quadra 700 and 900 in October 1991, when, , and  were still competing as wiring standards for Ethernet. Most of the beige-era Macintosh Quadra, Centris, and Power Macintosh series featured AAUI ports. However, as 10BASE-T gradually became the de facto standard, the beige Power Macintosh G3 was introduced in November 1997 with an port to connect directly to a 10BASE-T cable.