The 3B20D Processor & DMERT Operating System: Prologue

Copyright © 1983 American Telephone and Telegraph Company. Printed in U.S.A. The 3B20D Processor & DMERT Operating System: Prologue By J. M. SCANLON (Manuscript received June 23, 1982) The 3B20 Duplex Processor (3B20D) and its DMERT operating system represents a new and very important building block for the Bell System's stored program network. The first system to cut over was the network control point application in Kansas City, Missouri, on September 3, 1981. By year end 1982, the common 3B20D/DMERT processor system will have been in service supporting six different telecommunication applications across 65 different sites in 17 of the 20 Bell Operating Companies, including the Long Lines Division of AT&T. By year-end 1983, the number of different applications is expected to grow to ten and the number of sites to 300, covering all Bell Operating Companies. This very rapid buildup from first introduction to substantial deployment throughout the Bell System establishes the 3B20D/DMERT processor as a key element for the continued evolution of the Bell System's stored program network.1 The 3B20D Processor had its origins in exploratory work, begun in 1976, to establish a successor to the 3A processor2 deployed with No. 2B ESS and No. 3 ESS. 3 At that time, a specialized replacement processor for 3A was envisioned, which is the origin of the designation "3B." At about the same time, research in operating systems charac167 terized by the UNIX* operating system 4 and MERT 5 , and portable higher-level languages characterized by C,6 had matured to the point that the use of these techniques in real-time telecommunications applications became feasible and highly desirable.