SMALL, MODULAR COMMUNICATIONS SWITCHING SYSTEM WITH DISTRIBUTED PROGRAMMABLE CONTROL.

A telephone central office switching system, with economical application to small community dial office sizes, is described in this paper. Communication paths are spatially switched over a folded modular network built up in units of 200-inlet, 3-stage, code switch modules. A modular, distributed control concept is employed wherein the logic and flexibility of electronic stored-program control are spread over many points in system, in units whose processing capacity is equivalent to a microprocessor. Serial, asynchronous messages between any two control units are routed via a central information exchange unit whose number of communication parts is easily changed on a pluggable basis. Modularity is emphasized throughout the switching system for low startup cost, facile growth, and additions of feature-oriented service packages.