rd interface 280-1, a P1394 interface (I/F) block 290 for connection to an external 1394 device, an extension bus interface (I/F) block 300 to connect peripherals such as additional RS232 ports 300-6, display and control panels 300-4, 300-5, external ROM, DRAM 300-1, or EEPROM memory 300-2, a modem 300-3 and an extra peripheral 300-7, and a traffic controller (TC) block 310 that includes an SRAM/A