a processor module having a cache device and a system controller having a copy tag 2 of a tag of the cache device configure a system to which a protocol representing the states of a data block of the cache device by six states , that is , an invalid state i , a shared state s , an exclusive state e , a modified state m , a shared modified state o , and a writable modified state w can be applied . in order to implement the concept , information about a new state in a cache device of a requester is included in a reply packet from the cache device for transmitting the data block . after the completion of the snooping process of the tag 2 until the reception of the reply packet from the cache device for transmitting the data block and the determination of the next state , an object data block is locked in the tag 2 .