INFORMATION PROCESSOR, EXTERNAL DEVICE, HOST DEVICE AND COMMUNICATION METHOD

PROBLEM TO BE SOLVED: To perform one-to-many communication while holding interchangeability between a current memory card and a host device. SOLUTION: A plurality of memory cards 20 sharing signal lines CLK, BS, DIO for data transmission are connected to a host device 10, and the host device 10 assigns an identifier to the memory cards 20. When transmitting a command to the memory cards 20, the host device 10 inserts dummy data into the leading part of the command, and inserts an identifier into the terminal part of the command. Also, when performing data transmission between the memory cards 20 and the host device 10, the host device 10 inserts the dummy data into the leading part of data. COPYRIGHT: (C)2006,JPO&NCIPI