A receiver configured to receive a first command that contains a predetermined code string and a second command that does not contain the predetermined code string from a host computer. A first command analyzer configured to analyze and process only the first command received by the receiver. A buffer configured to temporarily store at least the second command received by the receiver. A second command analyzer configured to analyze and process the second command stored by the buffer. A sound generator configured to generate a sound when the first command analyzer analyzes the first command and determines that the first command includes a sound generating command. The first command analyzer analyzes the first command before the buffer temporarily stores the first command.