Interface Message Processor

impThe Interface Message Processor (or IMP), was essentially the first router, as routers would eventually become known. It was the first device built with the purpose of switching packets across a network and was intended for use with the ARPANET. It was created by BBN in the early 1960s using a Honeywell 516 minicomputer with special interfaces and software. Later the Honeywell 316 was used.

The first IMP arrived at UCLA on Aug. 30th, 1969 and was connected to an SDS Sigma-7 computer. The second IMP was delivered to the Stanford Research Institute on Oct. 1st, 1969 and attached to an SDS-940. On Oct.29th, the first communication between the two systems took place. IMPs connected the ARPANET until it was decommissioned in 1989, with the last one shut down at the University of Maryland.

IMPs were the grandfathers of today’s network devices such as routers and switches, which carry network traffic to their destinations across the internet and networks. They were the first generation of gateways to interconnect the different networks connected to the ARPANET. Without such pioneers as BBN and ARPA, the internet as we know it today would not exist.

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