Image Number 11 for United States Patent #6654269.
A memory cell of the association memory including a register, a transmission circuit, and a match circuit is provided. A register stores storage data when its own memory cell is not in the don't care state, and stores the don't care data in the adjacent memory cell when in the don't care state. A transmission circuit transmits the don't care data indicating that the other adjacent memory cell is in the don't care state to the other adjacent memory cell when both of the don't care data transmitted from the one adjacent memory cell and the don't care data stored its own memory cell indicate the don't care state. A match circuit outputs match data indicating the agreement when the storage data stored in the register and the search data supplied from the outside agree with each other.