IMP

networking

Interface Message Processor: the ARPANET's packet switch, a separate minicomputer sitting between a host and the network.

Putting the network's logic in its own machine was a design decision with consequences. Hosts differed wildly, and asking each to implement the network directly would have made the network hostage to the slowest vendor; the IMP presented one interface and absorbed the difference. It is the ancestor of the router as a distinct box rather than a function of a computer, and the reason the first network engineers worked on equipment nobody else in the building understood.

Also known as: interface message processor, interface message processors

← All glossary entries