Design of a Microprogram Control for a Processor in an Electronic Switching System

The processor in an electronic telephone switching system must be designed to efficiently and reliably process telephone calls. Because of the extended life span of a telephone switching system and the nature of the function it provides, it is advantageous to build a great deal of flexibility into the processor design. This paper provides details of a microprogram control design philosophy for the development of a medium-size processor∗that provides the required flexibility. The aspects of the microprogram control that make it very suitable for the design of a processor in a fault-tolerant system are also described.