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

Abstract

An associative memory, a router and a network system incorporating an associative memory are disclosed with high speed data transfer speed and low power consumption. An associative memory is constituted of a first circuit means for conducting a primary search operation for each single word of the storage data so as to exclude a single or plural bits of the storage data from the search object with use of an external search data input to the memory when the mask information corresponding to each single word is in a valid state; a second circuit means for selecting a single or plural words as a candidate data; a third circuit means for conducting a logical AND operation to obtain a matched mask logical AND information between each mask information corresponding to the selected candidate data, with assuming the valid state of the mask information as true; and a fourth circuit means for conducting a first logical operation between the matched mask logical AND information and the search data.