Microword length minimization in microprogrammed controller synthesis

The problem of microword length minimization is crucial to the synthesis of microprogrammed controllers in digital systems. Unfortunately, this problem is NP-hard. Although various enumerative and heuristic methods have been developed, usually they cannot provide fast and e cient solutions to a large size problem. In this paper, we rst formulate the problem into a graph partitioning problem. An e cient graph partitioning algorithm was developed that works by recursively extracting large size cliques from the graph. Furthermore, we employ a local search approach to reduce the microword length. This has resulted in an e cient algorithm that outperforms any existing technique available to solve the problem. We have tested our algorithm with practical microcodes. We compare our experimental results with other existing methods.