Metcalfe and Boggs build Ethernet at Xerox PARC
A memo about connecting Altos to a shared printer becomes the standard for local networks
Quick facts
- Co-inventors
- Robert Metcalfe and David Boggs, Xerox PARC
- Memo date
- 22 May 1973
- Working system
- 11 November 1973
- Technique
- Carrier-sense multiple access over shared coaxial cable
What happened
Xerox's Palo Alto Research Center (PARC) had built the Alto, an early personal computer, and wanted every Alto in the building connected to each other, to a newly built laser printer, and to the outside world through ARPANET. Robert Metcalfe, with colleague David Boggs, adapted ideas from the University of Hawaii's ALOHAnet, which broadcast data over radio, into a wired version running over coaxial cable, with no central controller. A node listened to the cable and only transmitted when it sensed the line was quiet, a technique called carrier sense. Metcalfe circulated a memo describing the scheme on 22 May 1973, though Boggs later argued the true birthday was 11 November 1973, the day the system first actually worked.
Why it matters
Ethernet let any number of computers share a single cable without a central switch coordinating them, a design so durable that later versions running on twisted-pair and fiber cable still use the same core Ethernet framing, decades after coaxial cable itself disappeared from offices.
How we know
The National Inventors Hall of Fame's induction page for Metcalfe and the IEEE's own Milestone documentation for Ethernet describe the PARC origin, the Alto/printer/ARPANET connection problem, and Boggs's co-invention.
Sources
- National Inventors Hall of Fame. NIHF Inductee Robert Metcalfe, Who Invented the Ethernet · Reputable sourceinvent.org · The domain "invent.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
- Engineering and Technology History Wiki (IEEE). Milestones:Ethernet Local Area Network (LAN), 1973-1985 · Reputable sourceethw.org · The domain "ethw.org" is on our Reputable source registry. · Link is live and its text matches the event's key terms (Jul 2026)
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