Medium Attachment Unit
A Medium Attachment Unit (MAU) is a transceiver which converts signals on an Ethernet cable to and from Attachment Unit Interface (AUI) signals. On original 10BASE5 (thicknet) Ethernet equipment, the MAU was typically clamped to the Ethernet wire via a vampire tap and connected by a multi-wire cable to the computer via a DA-15 port, which was also present on the network interface controller (NIC).