What is difterent about operating systems for telephone switching

Operating systems to provide resource allocation, concurrency control, and auministrative services are integral parts of general purpose computing systems. Electronic Switching Systems (ESS) are real time systems to control switching of a large number of phone calls. Control functions similar to those of operating systems exist in these ESS's but they are seldom distinguished nor structured as an operating system in the literature. This paper examines the characteristics of the telephone switching environment and applies commonly known operating system concepts to structuring software ano controlling of telephone switching. It is found that existing ESS software structures can be described in the framework of operating systems and that in general operating system concepts can be positively applied to new designs. However, special design considerations must be made in process structure, scheduling, and memory management to meet requirements of the switching environment.