| 摘要 |
A distributed data processing system including a general, passive, communications network, and a plurality of local systems which each have a central processing unit, associated memory, and at least one peripheral device. The control of the intercommunication is effected by respective system intercommunication processors, each interfacing one local system to the network. Each systems intercommunications processor is attached to the network by means of a respective communication module. A communication module has sequences for controlling in a first sequence of steps an addressed logical link from a source local system to a single destination local system and in a second sequence of steps controlling a broadcast logical link from a source local system to one or more destination local systems. The sequences include a plurality of conditionally executable steps, namely, logical link establishing steps, logical link maintaining steps, logical link closing steps, logical link breaking steps, error detection and retrying steps, and logical link cancelling steps. For establishing a broadcast logical link the source station does not need to know initially either the number of connected links or the number of potential destination stations. All establishing steps comprise inherent priority level signalizations. In a destination station conflicts are resolved by choosing a higher priority addressed logical link over a lower priority addressed logical link and a broadcast logical link over any addressed logical link.
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