A procedure is described which permits applications problems coded in a Higher Level Language to be compiled to microcode for horizontally microprogrammed processors. An experimental language has been designed which is suitable for expressing computationally oriented problems for such processors in a distributed processing environment. Source programs are compiled first to a machine independent intermediate language and then to a machine dependent form consisting of elementary microoperations, with optimizations performed during each step. The microoperations are then compacted into executable microinstructions for a specific target machine. The procedure has been implemented for experimental purposes and used to compile several different types of applications programs. The experimental results are presented with an interpretation and analysis, along with recommendations for future study.

A procedure is outlined for describing the microarchitecture of a horizontal processor such that a retargetable Microprogram Compiler System can incorporate the description to generate microcode for that processor. The microarchitecture description methodology is an organized approach to defining a machine's microinstruction formats, fields, and microorders; its hardware elements; its microoperation usage rules; and its behavioral rules. To a large extent, the description procedure can be performed interactively. The link between the microarchitecture description and the microprogram compiler, termed the instruction set interpretation mechanism, is also described. Preliminary application of the microarchitecture description methodology to several real processors has shown that, despite some problems, the procedure shows promise for significantly reducing the time required to retarget a microprogram compiler.

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