Steven L Andersen

US Patent:

44096569, Oct 11, 1983

Filed:

Dec 21, 1981

Appl. No.:

6/333068

Inventors:

Steven C. Andersen - Prior Lake MN
Thomas P. Penkauskas - Eagan MN
James W. Kassel - St. Paul MN
Stephen O. Newcomer - Apple Valley MN

Assignee:

Her Majesty the Queen, in right of Canada as represented by the Minister
of National Defense - Ottawa

International Classification:

G06F 304
G06F 504
G06F 922
G06F 1120

US Classification:

364200

Abstract:

A node device for use in a digital data processing and communications system of the type utilizing a bus organization for facilitating the interconnection of a large plurality of digital data processing devices (user devices) in which redundant cables are employed. The node devices are interposed between the user devices and the redundant cables to permit automatic reconfiguration of the interconnection of the user devices in the event of malfunctioning or severing of one or more of the cable sets within a minimum period of time. The node devices provide the user devices with the structure needed to detect and diagnose system problems and to effect recovery procedures. In accordance with the invention, one of the plurality of nodes functions as the Bus Controller and by sampling the remaining nodes in the system, it determines the priority with which user devices may transmit or receive data over the bus. Each of the nodes employed is substantially identical and any one may be selected to function as the Bus Controller. Each includes a Microprogrammed Controller and necessary firmware to permit the controller to function in conjunction with special purpose hardware including a Programmable Logic Array (PLA) configured to perform a pre-processing function on control line inputs so that poll/response traffic on the active cables can continue with a minimum of delay.