Modernization of the Suburban ESS: Overview: Evolution of the Suburban ESS

T h e No. 2 Electronic Switching System (ESS), 1 designed in the 1960s to provide E S S capabilities to suburban communities, was developed under t h e same constraints as other large real-time control systems of t h a t era. Memory was expensive and processors were not powerful enough to compensate for inefficiencies in software. As a * Bell Laboratories. °Copyright 1983, American Telephone & Telegraph Company. Copying in printed form for private use is permitted without payment of royalty provided that each reproduction is done without alteration and that the Journal reference and copyright notice are included on the first page. The title and abstract, but no other portions, of this paper may be copied or distributed royalty free by computer-based and other informationservice systems without further permission. Permission to reproduce or republish any other portion of this paper must be obtained from the Editor.