Associative memory having a mask function for use in a network router

Abstract

When one or more storage data are coincident with single search data (), an associative memory () carries out logical sum for all of storage data with a valid state for storage data as true. The result of logical sum is used as matched data logical-OR information. In a primary searching operation, the associative memory () is supplied with the search data () to provide the matched data logical-OR information on matched data logical-OR lines. Then, the associative memory () carries out a secondary searching operation supplied as search data with the matched data logical-OR information obtained by all of storage data coincident upon the primary searching operation. Only a match line () coincident with the matched data logical-OR information is selected as the secondary search result. The associative memory is used in a network router to calculate an optimum memory address signal () by encoding the selected match line (). In response to the memory address signal (), a memory data signal () enabling shortest network connection is produced as a transfer network address (). The transfer network address () is combined with a data area () and a destination network address () contained in input transfer data () to produce output transfer data ().