System 75:Switch Services Software
W. Densmore, Ray Jakubek, M. J. Miracle, John H. Sun · AT&T Technical Journal · 1985
The switch services software of System 75 provides the basis for an extensible office communication system, supporting a wide variety of voice and data-switching services. This paper presents the software architecture of the System 75 switch services. The concepts of user, group, and process-per-call form its foundation. We introduce the architecture by stepping through a simple station-to-station phone call, and proceed to the derivation of a call model based on the topology of a call. This call model is realized as a layered set of cooperating processes that execute under the Oryx/Pecos Operating System on the System 75 switch processor. The software layers and processes are discussed and a call walk-through is used to illustrate the process interactions.