====== 3Com - 3c108 AUI transceiver (Medium Attachment Unit, MAU) ======

===== Overview =====

{{ networking:3c108-a.jpg?100|}}[[https://en.wikipedia.org/wiki/Attachment_Unit_Interface|AUI]] to thick ethernet transceiver designed to connect to network cards with an AUI 15 pin D socket. This interfaced to a 50 Ohm coaxial cable via N-type coax connectors and provided a connection "Drop". 

The correct name for this is a ''Medium Attachment Unit''.


{{networking:3com-isa-aui.jpg?100 |3Com ISA network card with AUI port.}}
The transceivers are powered from a source in the network card, the tx and rx connections are over a twisted pair.

The card on the right is an old 3Com one, it has from bottom to top, a thin ethernet BNC socket ([[https://en.wikipedia.org/wiki/10BASE2|10Base-2]]), and [[https://en.wikipedia.org/wiki/Attachment_Unit_Interface|AUI port]] for connecting to the 3C108 transceiver (Using a 15pin D plug to 15pin D socket, 3 sets of twisted pairs, Tx, Rx and power) and at the top, a [[https://en.wikipedia.org/wiki/Ethernet_over_twisted_pair|10Base-T]] RJ45 connector. 

===== Coax Interface =====

Two basic versions of thick ethernet taps were produced, this on is an example of where the Yellow Coax cable has to be severed and an N connector plug crimped or soldered to each end, these are then screwed in to the tap.

The other type used a sharp pin to pierce the cable and could be installed without interruption to service, these were often referred to as "Vampire Taps".

{{:networking:pinsforcoax1.png?200|}}
{{:networking:pinsforcoax2.png?200|}}
{{:networking:pinsforcoax3.png?200|}}

This MAU seems to have the option to install either the N connector module or something else from the way it is constructed.