Content addressable memory capable of changing priority in priority encoder

Abstract

A content addressable memory includes a plurality of word memories which respectively have assigned addresses, and each outputs a match/mismatch signal representing storage or no storage of a data item matching search data in a search mode, a priority encoder which output addresses of word memories which output the match signals in the search mode in predetermined fixed priority order, a first prior word-memory setting section for setting a first prior word memory, and a priority changing part which masks the match signals output from upper-positional word memories of the word memories, which correspond to word memories having upper positions compared with the first prior word memory in the fixed priority order in the priority encoder, and transmits signals representing that the word memories having the upper positions output no match signals to the priority encoder.