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Leonard Kleinrock with the first IMP.




The Interface Message Processor (IMP)


Computers were not dependable enough to deliver messages; interconnection proved problematic. The solution was to create a network of small, reliable processors called IMPs.
"The network is thus a store and forward system and as such must deal with problems of routing, buffering, synchronization, error control, reliability, and other related issues. To insulate the computer centers from these problems, and to insulate the network from the problems of the computer centers, ARPA decided to place identical small processors at each network node, to interconnect these small processors with leased common-carrier circuits to form a subnet, and to connect each research computer center into the net via the local small processor."
- The interface message processor for the ARPA computer network
In video:
Leonard Kleinrock:
Engineer, computer scientist, Internet pioneer, researcher of queuing theory, contributor to packet switching, and professor of computer science at UCLA.
Picture
A 1969 Datapoint 3300 Terminal.




The Terminal Interface Processor (TIP)

The TIP connected to terminals, rather than hosts.
Without IMPs, packet switching couldn't be implemented. These processors, now called routers, are still in use today. Without them, the Internet would not be reliable enough to support millions of users and allow for widespread benefits.