(Or "MAC address") The physical address identifying an individual Ethernet controllerBoard. 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)