<P> The Interface Message Processor (IMP) was the packet switching node used to interconnect participant networks to the ARPANET from the late 1960s to 1989 . It was the first generation of gateways, which are known today as routers . An IMP was a ruggedized Honeywell DDP - 516 minicomputer with special - purpose interfaces and software . In later years the IMPs were made from the non-ruggedized Honeywell 316 which could handle two - thirds of the communication traffic at approximately one - half the cost . An IMP requires the connection to a host computer via a special bit - serial interface, defined in BBN Report 1822 . The IMP software and the ARPA network communications protocol running on the IMPs was discussed in RFC 1, the first of a series of standardization documents published by the Internet Engineering Task Force (IETF). </P> <P> The idea of an "Interface computer" was first developed in 1966 by Donald Davies for the NPL network in England . The same idea was independently developed in early 1967 at a meeting of principal investigators for the Department of Defense's Advanced Research Projects Agency (ARPA) to discuss interconnecting machines across the country . Larry Roberts, who led the ARPANET implementation, initially proposed a network of host computers . Wes Clark suggested inserting "a small computer between each host computer and the network of transmission lines", i.e. making the IMP a separate computer . </P> <P> The IMPs were built by the Massachusetts - based company Bolt Beranek and Newman (BBN) in 1969 . BBN was contracted to build four IMPs, the first being due at UCLA by Labor Day; the remaining three were to be delivered in one - month intervals thereafter, completing the entire network in a total of twelve months . When Massachusetts Senator Edward Kennedy learned of BBN's accomplishment in signing this million - dollar agreement, he sent a telegram congratulating the company for being contracted to build the "Interfaith Message Processor". </P> <P> The team working on the IMP called themselves the "IMP Guys": </P>

Where were the first 4 interface message processors located