Content-addressable memory having control circuitry and independent controls for match and write cycles

摘要

A content-addressable memory (CAM) consisting of an array of memory cells arranged in a matrix by rows and columns is disclosed in which each memory cell includes a pair of cross-coupled CMOS inverters for storing a representation of a single bit. The bits in each row of memory cells constitute a keyword. Keywords are entered into the memory one row at a time. All of the stored keywords are compared to a single search word simultaneously during a match operation. The CAM is prepared for a match operation by placing a charge on a match line associated with each row. If all the bits of the search word match the bits of the stored keyword, the associated match line remains charged producing a match signal for the row of memory cells. If any bit of the search word does not match the corresponding bit of the stored keyword, the associated match line is discharged producing a no-match signal for the row of memory cells.