A method of operating a memory controller includes allocating a new entry whenever a write command is input from a host; and transferring data corresponding to an entry in a specific state among a plurality of states to the host in response to a read command output from the host, wherein the plurality of states are a FREE state, a WRITE state, a WRITE OLD state, a READ state, a PEND state, a PEND OLD state, a CACHE state, and a DEL state, and the specific state is at least one of the PEND state, the PEND OLD state, or the CACHE state.