<P> The ARPANET was operated by the military during the two decades of its existence, until 1990 . </P> <P> The initial ARPANET consisted of four IMPs: </P> <Ul> <Li> University of California, Los Angeles (UCLA), where Leonard Kleinrock had established a Network Measurement Center, with an SDS Sigma 7 being the first computer attached to it; </Li> <Li> The Augmentation Research Center at Stanford Research Institute (now SRI International), where Douglas Engelbart had created the ground - breaking NLS system, a very important early hypertext system, and would run the Network Information Center (NIC), with the SDS 940 that ran NLS, named "Genie", being the first host attached; </Li> <Li> University of California, Santa Barbara (UCSB), with the Culler - Fried Interactive Mathematics Center's IBM 360 / 75, running OS / MVT being the machine attached; </Li> <Li> The University of Utah School of Computing, where Ivan Sutherland had moved, running a DEC PDP - 10 operating on TENEX . </Li> </Ul> <Li> University of California, Los Angeles (UCLA), where Leonard Kleinrock had established a Network Measurement Center, with an SDS Sigma 7 being the first computer attached to it; </Li>

What was the killer application that led to the early expansion of arpanet