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ARPANET Design Session

Last Edit: 10/01/17

The ARPANET Design Session was an important meeting of computer scientists who would discuss plans to build the first American packet switching computer network. The meeting was held in April 1967, in Ann Arbor, Michigan. Ann Arbor is a medium sized city that is located in Washtenaw County, within the US state of Michigan.

At the ARPANET Design Session, the design plans were preliminary in nature, and were led by Lawrence 'Larry' Roberts. Roberts had called for each location - four sites - to write their own software to interface with the proposed ARPANET. Each location - which were universities and research institutes in the US - had a different host computer and operating system; the task of writing this interface software appeared formidable.

It was at the end of this meeting that Wesley Allison Clark would suggest an alternative to Larry Roberts. Wesley Allison Clark is credited as being the inventor of the first minicomputer (LINC computer); which would evolve to become the personal computer. Clark suggested that the host computer of each location should not connect directly to the network: instead a minicomputer should be placed in-between the host computer and the network communication lines.

Each network location would have a minicomputer and the minicomputer would be identical. The minicomputer would act as the interface to the network, and the host computer would only need to write software to interface with the minicomputer; this would be simpler than each host computer writing their own interface software. Another advantage of the minicomputer was that it would lower the load placed upon the host computers.

Larry Roberts 'bought' into Clark's idea, and the minicomputer - named Interface Message Processor - would be an essential component of ARPANET. The ARPANET Design Session was an influential meeting in the history of computer networks. Interface Message Processors would evolve into routers, which are an integral component of the Internet.