Three level distributed control for networking I/O devices.

摘要

A three level microprocessor based nodal architecture for a local area network communication system is disclosed. The processing responsibility for establishing a communication link between an initiating I/O device and a recipient I/O device and for subsequent two way data exchange between the initiating and recipient devices are shared between three levels 1, 2, 3 of digital processing capability in such a manner as to demand the least amount of time from the highest, most intelligent processing level (1) common to all devices. Each I/O device whether it be a digital terminal, computer or telephone set interfaces with the nodal system through a middle level of processors (20). Voice, video or data can be sent externally of the node (12) via a coupling network (14), or routed back through the node (12) to another middle level processor (20) to an associated I/O device. A priority scheme utilizing a separate control data channel coupling the plural nodes at the third processor level (3) operates to maintain substantially full data density on the data coupling network.