The heuristic synthesis of applications-oriented microcode

This paper describes an algorithm for the synthesis of applications-oriented microcode for a dynamically microprogrammable computer. The need for such an algorithm is expressed by Reigel, Faber, and Fisher as an integral step in the solution of the tuning problem, or the problem of modifying a system architecture in order to optimally solve a given problem. This modification of architecture takes place through synthesis of microprograms that are stored in writable control storage. Writable control storage permits each class of user application programs to execute with a specialized instruction set, or architecture. A synthesis algorithm provides a method for generation of these specialized architectures. The required synthesis algorithm should be autonomous, should not require apriori knowledge of user application, and should be adaptable to day-by-day changes in user problems.

Current attempts at tuning architectures can be considered as manual tuning. Heuristic tuning is suggested as an automization of the manual tuning process. Several phases of heuristic tuning are summarized. The architecture synthesis phase is considered in depth and an algorithm for microprogram synthesis is given. Several examples of the synthesis algorithm are presented and the expected execution improvements are shown.