Traffic Service Position System No. 1B: Retrofitting the Processor

Over 150 Traffic Service Position System No. 1 (TSPS No. 1) offices1 are in service in the United States. These systems give fast, efficient toll operator services to over 95 percent of the Bell System main stations. The TSPS No. 1 consists of a Stored Program Control No. 1A (SPC 1A) and numerous peripheral units. The SPC 1A has performed well since its initial introduction into service in Morristown, New Jersey, in 1969.2 The development of the TSPS No. IB introduced a modern 3B20 907 Duplex (3B20D) Processor with its peripherals and a Peripheral System Interface (PSI) into TSPS. 3 The 3B20D Processor and the PSI together are called the SPC IB.4 The PSI connects the 3B20D to the existing TSPS peripherals in such a manner that the interface to the SPC IB is the same as the interface to the SPC 1A. Since many TSPS No. 1 sites are approaching real time and memory exhaust and the new processor capabilities are necessary for new features, a procedure has been developed to allow in-service TSPS sites to retrofit to the SPC IB. This procedure requires advanced planning for floor space, connectorization of existing buses, and some hardware modifications. Special procedures and tools are used to ensure that the SPC IB can properly interface with the existing periphery before the new processor is in control of call processing. After cutover and following sufficient soak time on the SPC IB during which assurance tests are run, the SPC 1A can be removed from the office. Unlike commercial processor upgrades, where the system is taken off-line, the replacement of the SPC 1A with the SPC IB must be performed with virtually no interruption of call processing.