Source : Free On-Line Dictionary of Computing

Apple Attachment Unit Interface
     
         (AAUI) A 14-position, 0.050-inch-spaced
        ribbon contact connector.  Early {Power Macintosh} and Quadras
        had an AAUI (Apple Attachment Unit Interface) {port}
        (rectangular shaped) for {Ethernet}, which requires a
        {transceiver}.  To use {twisted pair} cabling, you would need
        to get a {twisted pair} transceiver for the computer with an
        AAUI port.  Some {Power Macintosh} computers had both an AAUI
        and {RJ-45} port; you can use one or the other, but not both.
     
        The pin-out is:
     
          Pin   Signal Name     Signal Description
          ----  --------------  ---------------------------------
          1     FN Pwr          Power (+12V @ 2.1W or +5V @ 1.9W)
          2     DI-A            Data In circuit A
          3     DI-B            Data In circuit B
          4     VCC             Voltage Common
          5     CI-A            Control In circuit A
          6     CI-B            Control In circuit B
          7     +5V             +5 volts (from host)
          8     +5V             Secondary +5 volts (from host)
          9     DO-A            Data Out circuit A
          10    DO-B            Data Out circuit B
          11    VCC             Secondary Voltage Common
          12    NC              Reserved
          13    NC              Reserved
          14    FN Pwr          Secondary +12V @ 2.1W or +5V @ 1.9W
          Shell Protective Gnd  Protective Ground
     
        AAUI signals have the same description, function, and
        electrical requirements as the {AUI} signals of the same name,
        as detailed in {IEEE 802.3}-1990 CSMA/CD Standard, section 7.
     
        (2000-02-10)