From Boing Boing, along with this:
Behind an ordinary door in a nondescript room hosting several printers and copiers at PARC is the world's first Ethernet cable. In 1973, Bob Metcalfe sent an internal memo to his colleagues at Xerox proposing a local system of interacting workstations, files, and printers. The devices would all be linked by one coaxial cable, he said, and would run within a local area network. He called the system an Ether Network, or Ethernet. By 1976, there were over 100 devices linked into Metcalfe's local network, and it was even used to test out the world's first laser printer, which was being developed concurrently in another research facility within Xerox. Metcalfe and his assistant David Boggs published their findings in the Association for Computing Machinery later that year. The rest is history.
Go to the Boing Boing link for Metcalf's original drawings of the system.