1. A logical circuit automatic design system for automatically synthesizing a special purpose processor which is optimized to perform a necessary signal processing algorithm, the system comprising: storage means for storing plural architecture templates of a processor; template selecting information generating means for generating template selecting information based on said necessary signal processing algorithm; output means for outputting at least one architecture template of a processor; second input means for selecting, based on said template selecting information, one of said at least one architecture template outputted by said output means; and synthesizing means for automatically synthesizing the special purpose processor which is optimized to perform said necessary signal processing algorithm using the selected architecture template.