A New Look at Logic Synthesis

Despite many attempts to generate hardware implementations automatically from functional specifications, the literature does not record any commercial success. Previous efforts have dealt primarily with technology-independent primitives and have emphasized circuit minimization. However, larger scales of integration have made other design requirements and technology restrictions as important as circuit count, and have increased the cost of making an engineering change. Thus it is becoming increasingly important to insure that initial chip designs are correct. This paper outlines an investigation into the feasibility of logic synthesis in this new context. A system is described which will produce a naive implementation automatically from a functional specification, and then will interact with the designer, allowing him to evaluate it with respect to these many factors, and to improve it incrementally by applying local transformations until it is acceptable for manufacture. The use of simple local transformations will insure correct implementations, will isolate technology-specific data, and will allow the total process to be applied to larger VLSI designs. This approach has been tested on the design of a single chip with encouraging results. A prototype synthesis system is now being used to perform further experiments.