Microprogramming is a basic technique that realizes functionally specialized processors in a functionally distributed multiprocessor system which consists of many small processors. In such a multiprocessor system, it is necessary to change processor functions dynamically in order to back up a heavily loaded processor or a failed processor by a lightly loaded processor. This paper proposes a mechanism for exchanging processor functions in firmware level and shows a hardware organization which realizes the mechanism in an experimental system. In order to clarify the design conditions of an operating system and microprograms, the performance of the mechanism is analyzed from the load balancing point of view. Moreover, the conditions which the mechanism must satisfy are derived.

This paper discusses the design of interconnection modules for a multiprocessor system which consists of many small and functionally specialized processors. It is proposed that the information, i.e. programs, data etc., used in the system should be divided into three categories; private information, command data and shared data, according to the analysis of software simulation results. Private information is stored in a memory provided exclusively for each processor. Command data is transferred directly between processors to initiate a function in other processors. Shared data is stored in a memory shared by several processors. For command data and shared data, two different connection modules are provided; the interprocessor connection module using common bus technique, and the processor-memory connection module using crossbar switch technique. The effects of information partitioning on the performance and cost of the system are analyzed. It is verified that the interprocessor connection module technique is preferable than a few possible alternatives through the design analysis and the implementation of a pilot model system.