In 1983, the Department of Defense's Advanced Research Projects Agency Network (ARPANET) officially switched from the Network Control Program (NCP) protocol to Transmission Control Protocol/Internet Protocol (TCP/IP). Six months later, ARPANET was split into two subnetworks--ARPANET, which would continue to serve researchers and eventually be renamed as the Internet, and MILNET, a network the military used to share unclassified information.
The original ARPANET had only a single network address, says Robert Braden, a project engineer for the University of Southern California's Information Sciences Institute. "When you split that address using TCP/IP, you could add more computers to the network connected by routers," says Braden, who wrote the TCP/IP code for UCLA's IBM mainframe in preparation for the 1983 switchover.
"This was the beginning of the ability to connect different networks together." The launch of the Internet heralded a new way of looking at computers--as communications devices rather than simply as number crunchers.