ABSTRACT
Distributed communication systems involve network communications between self-contained, autonomous entities. In this situation, there is no master-slave relationship and the computer systems operate in a cooperative fashion. In actual practice, a communications network frequently involves all three of these types of information transfer operations at different levels of the system. Therefore, it is often ambiguous to attempt to classify a system as belonging to only one specific category of operation. For example, a group of host processors may be interconnected through a distributed communications network, while each of them is also serving a variety of subsystems. These subsystems may involve both centralized and decentralized communications at different locations within their heirarchy. Even the lowest level of a heirarchy, such as a machine tool control system, may incorporate multiple CPUs that work together to provide the necessary data processing capability (servo control, command interpolation, I/O, etc.).
