(Or "MAC address") The physical address identifying an individual Ethernet controller board. An Ethernet addess is a 48-bIT number aabbccddeeff where a-f are hexadecimal digITs. The first 24 bITs, aabbcc, identify the manufacturer of the controller. The Ethernet address is hard-wired on some controllers, stored in a ROM on some, and others allow IT to be changed from software. IT is usually wrITten as six hexadecimal numbers, e.g. 08:00:20:03:72:DC. See also ARP, Internet address. (1996-02-21)