The Advanced Research Projects Agency Network.
A pioneering long-distance network, it was created on behalf of the U.S. Department of Defense as a resilient means of communication for various U.S. agencies. The first node was created at the University of California at Los Angeles and was the backbone of the Internet until 1990, after the transition to the TCP/IP protocol was completed in 1983.
The first message was between an SDS Sigma 7 operated by a team led by Professor Leonard Kleinrock at UCLA and the FDS 940 operated by a team led by Douglas Engelbart at the Stanford Research Institute.
Fun facts: * From this event is that the message text was the login word "loggin" but only the letter "l" and the letter "o" are transmitted, when typing the "g" the system crashes and crashes. About an hour later, having recovered from the crash, the SDS Sigma 7 computer manages to perform a full login.
* The Sigma 7 was discontinued in 1970 when Xerox, which bought SDS in 1969, withdrew from the mainframe market.
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