Patent ID: 7360001

Claim:
An external connection device connectable to a host device, said external connection device comprising: a parameter register operable to store a parameter; a command register operable to store an operation control command provided by the host device; and a controller operable to refer to the operation control command stored in the command register and to perform operation control specified by the operation control command; said parameter register and said command register being accessed by the host device based on a transfer protocol command (TPC) issued from the host device; a command set of the TPC including a first register write command for requesting transmission of an arbitrary parameter from the host device to said external connection device and storage of the transmitted parameter in said parameter register, a second register write command for requesting transmission of an arbitrary operation control command from the host device to said external connection device and storage of the transmitted operation control command in said command register, and a third register write command for requesting transmission of an arbitrary operation control command and an arbitrary parameter from the host device to said external connection device, storage of the transmitted operation control command in said command register, and storage of the transmitted parameter in said parameter register.