Patent ID: 8364872

Claim:
An apparatus comprising: a master; a slave in communication with the master, the slave including: a central processing unit configured to generate an acknowledgement signal (ACK) if the master attempts to send a command, the ACK allowing a transfer of the command in accordance with a result of checking whether the command to be transmitted is one of a write command and a read-out command and a result of checking whether a processing of a previous command previously sent by the master is entirely completed; and a storage unit configured to store one of a written data and read-out data under control of the central processing unit, wherein the master sends the command to the slave in response to the ACK signal transferred from the slave, and wherein the ACK siqnal is generated when the command to be transmitted is determined as the read-out command irrespective of whether or not the processing of the previous command previously sent by the master is determined as entirely completed.