Data communication system

摘要

A data communication system for providing data transmission between a plurality of individually addressable local computer networks, by utilizing single node switching across a common passive bus medium. The passive bus medium is characterized as having a plurality of separate conductors of limited length that are each commonly connected to individual bus interface circuits for each local computer network. Each bus interface circuit has a number of dedicated address data ports, message data ports and control ports that are connected to separate dedicated conductors of the passive bus medium for transmitting data to and receiving data from other local computer networks. Each message transmission of data on the passive bus medium is divided into a number of mini-packets each of which contain a number of parallely transmitted bits corresponding to the number of dedicated address and message conductors in the passive bus medium. Each mini-packet is separately transmitted on the passive bus medium and separately acknowledged by the designated receiving bus interface circuit. Mini-packets are of two types for each message. The first group of mini-packets precedes the second group and contains destination address in its header portion and word count information in its message portion. The second group constitutes the remainder of the message and each mini-packet of this group contains the source address in the header portion and message data in the message portion.