Interface Message Processors for the ARPA Computer Network
A 1975 technical report from Bolt Beranek and Newman Inc. in Cambridge, Massachusetts, written by Frank E. Heart and aimed at engineers and computing specialists building the ARPA computer network. The one picture is a schematic diagram of how users, TIPs, TIPSERs and RSEXECs connect across the ARPANET, drawn as overlapping circles and labelled nodes with dashed links. A designer could borrow its clean node-and-link diagram style for showing networked systems and connections.
