Asynchronous Serial Interface for Connecting a PDP-11 to the ARPANET (BBN 1822)

This document, Technical Report No. 116 from July 1976, describes an interface designed by Ronald C. Crane to connect any PDP-11 computer to the ARPANET or the Packet radio network. The interface connects to an IMP (Interface Message Processor) on one side, adhering to BBN report number 1822 specifications, and to a 16-bit parallel interface (DRV-11 or DR11-C) on the PDP-11 side. The interface card itself is a double-height board that plugs into a PDP-11 peripheral slot. The report details the interface's circuits, programming, and diagnostics, including its transmit and receive sections, electrical specifications, connectors, and a loopback test. It also provides information on the DR11-C interface and a parts list for the interface. The research was supported by the Defense Advanced Research Projects Agency under ARPA Order No. 2494.