Between 1969 and 1977, ARPANET grew from a network of four computer sites to one with 111 computers belonging to universities, research facilities and the military. Using satellite links, ARPANET connected computer systems in the continental United States to computers in Hawaii and Europe. Even though the network had grown, few people actually had access to the system. In general, the public remained unaware of ARPANET's existence.
Other ARPANET networks began to go live, including USENET, Ethernet, CSNET and BITNET. The ARPANET Request for Comments 827 established an External Gateway Protocol that made it possible for separate networks to access each other, even though access to ARPANET was still restricted for official use. In 1983, the military section of ARPANET split off from the network; its only connection to the larger network was a few e-mail gateways. The military renamed its smaller network MILNET, which would later become part of the Department of Defense Data Network (DDN) [source: Living Internet].
In 1986, five supercomputer centers formed a network called NSFNET. Before long, NSFNET grew to include several universities in its network. Other networks began to consolidate into larger systems. People referred to this larger collection of networks and gateways as the Internet. While the era of the personal computer began in the late 1970s, the Internet still remained a resource for universities, corporations and the government.
ARPANET's infrastructure was beginning to show its age. The system's IMPs weren't as efficient or powerful as the computer nodes in other networks. Organizations on ARPANET began to transition to other networks, mainly NSFNET. In 1990, DARPA pulled the plug on the ARPANET project. The organization's goals had been met. The United States had a nationwide computer network that not only linked powerful resources together, but also could continue operating if a significant portion of the network stopped working. Even more impressive, this network now spanned the globe, connecting computers from one side of the world to the other.
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