At the end of 1981, over 150 Traffic Service Position System No. 1 (TSPS No. 1) offices were in service, equipped with Stored Program Control No. 1A (SPC 1A) processors. Some of these sites had reached the system capacity with respect to real time or memory. The new SPC 1B, which contains a 3B20 Duplex (3B20D) Processor and a Peripheral System Interface (PSI), provides the TSPS No. 1B with additional processor capabilities for additional capacity and future features. This article discusses the techniques used for achieving a smooth retrofit from the TSPS No. 1 to TSPS No. 1B with virtually no interruption of call processing. Special procedures and tools were developed to introduce the SPC 1B onto existing buses and to verify the interfaces with existing peripherals by means of a cycle‐stealing mechanism, while the SPC 1A continues to handle call processing. These procedures were used successfully at the first such retrofit in Redwood City, California, on March 13, 1982. During 1982, 34 additional sites will be retrofitted by Western Electric to accomplish the initial phase of the planned retrofits to TSPS No. 1B.

This paper describes the verification and evaluation procedures followed in the development of new features for the Traffic Service Position System (tsps). Beginning with the definition of new feature requirements, these procedures are adhered to throughout the tsps development cycle. Hardware and software designs are reviewed to verify that all requirements are met and to ensure that Bell System standards for reliability are maintained. Finally, both system laboratory and site testing are performed to verify the proper implementation of each new feature and to evaluate the overall performance of the tsps.

This paper describes factory system testing for the 5ESS™ switch. Factory system testing is performed using standard maintenance and diagnostic features of the 5ESS switch. The design of the factory system testing process is based on the distributed architecture of the 5ESS switch and is described in this paper. The system-level requirements that each 5ESS switch must meet before shipment to the field are also discussed.

Large software projects require control procedures to ensure that changes to code can be made systematically. Programmers, however, wish to be able to make changes to their programs without being bothered by administrative considerations. This paper explores the attitudes of people toward change control and the problems associated with establishing a workable system.