Essential Guide to Computing: The Story of Information Technology, The

Local Area Networks

Early in the microcomputer era, there were a variety of contenders in the LAN arena. However, the dust has now settled, and there are only two important ones left—Ethernet and Token Ring. Others, such as ARCnet and Appletalk, have shares of the market that are vanishingly small.

Ethernet

Ethernet, originally developed at Xerox's Palo Alto Research Center (PARC), is a bus-based local area network strategy. Ethernet is also baseband—only one connection can operate on a wire at one time. The wire is shared through an approach known as Carrier Sense Multiple Access/Collision Detection (CSMA/CD). Ethernet nodes listen to the wire to which they are attached to see if anyone else is broadcasting (carrier sense). If all is quiet, ...