ABSTRACT
Connection between the multiple microprocessor and the other devices in the network is through various common carriers or private transmission methods. Access is determined by which station has the token; that is, only one station at a time, the one with the token, is given the opportunity to seize the channel. The hub based architecture is an effective means of controlling the signal quality because the hub isolates each Resource Interface Module port from the main coaxial cable. Voice grade lines must be used with the same constraints and guidelines as for twisted pairs. Coaxial cable consists of a center conductor surrounded by a shield. Fiber optics is a reliable communications media which is rapidly becoming cost competitive when compared to other high speed transmission methods. The amount of data coded on the signal can be increased by selecting four or eight values for the characteristic being modulated; this is not generally done with frequency shift key.
