The maintenance experiences of the DTS Division of the Harris Corporation are described. Harris DTS supports large real-time software systems with very high reliability requirements. Maintenance goals, the evolution of maintenance methodologies and the current methodology in use are described. The impact of this current methodology on personnel organization, the development process, and support tools is discussed.>

This paper describes the system architecture of the Harris 20-20, an integrated voice/data network switch. Both hardware and software aspects of the system are presented. The hardware buses and all major assemblies are identified and described. The architecture is innovative in that the system accommodates both North American and European standard multiplex equipment. The software design permits the subsystems to all run on a single microprocessor or to be distributed over multiple processors with no change to the application-level software.