22nd May 1973
Bob Metcalfe invents Ethernet

Ethernet was developed at Xerox PARC in 1973. Bob Metcalfe documented his ideas in a memo sent on the 22nd May 1973.

Ethernet is a set of networking protocols that allows locally-connected devices to communicate without talking over each other. It provides a set of rules that specify how communication should take place. For example, devices should make sure that no other device is sending messages before they start communicating.

The primary motivation for developing Ethernet was to allow the many Alto workstations at Xerox PARC to connect to the the world’s first networked laser printer.

Ethernet is named after "luminiferous ether", a since-disproven theoretical substance believed to be the medium for the propagation of electromagnetic waves in the late 1800s.

In 1975, Xerox filed a patent application listing Metcalfe, David Boggs, Chuck Thacker, and Butler Lampson as inventors. U.S. Patent 4063220, "Multipoint data communication system with collision detection" was granted on 13th December 1977.

Related information:

• The Centre for Computing History: Bob Metcalfe
• Wired: Everything You Need to Know About Ethernet

Image:

• 1977 hand-drawn diagram by Bob Metcalfe describing Ethernet.
  Credit: Bob Metcalfe, via IEEE 802.3 Working Group

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