Abstract: The present invention is directed to an information terminal device. A memory card 14 stores a serial number MID of the memory card 14 and a MID register program for registering the serial number MID in the information terminal device 10. At starting the information terminal device 10, the MID register program is downloaded from the installed memory card 14 and the serial number MID stored in the memory card 14 is stored in a non-volatile flash ROM 30 in accordance with the program. Then, the MID register program is cleared out of the memory card 14 and the MID register program on a SDRAM 32 downloaded to the information terminal device 10 is made invalid. Such processing prevents the serial number of the memory card 14 from being thereafter stored in the other information terminal device 10.

Abstract: A vehicle onboard device having characteristics capable of being changed communicates with a vehicle to set a characteristic value to an optimum value. Parameters for setting conditions of an electronic device are called out of an E.sup.2 PROM 14.sub.i of the vehicle 10.sub.i and are transmitted to a technology center 40 via a dealer 20.sub.1, and an information center 30.sub.1. Each dealer 20.sub.1, the information center 30.sub.1, and the technology center 40 accumulate the parameters. The technology center 40 can collect the parameters of numerous vehicles and characteristic values for electronic control of each of the vehicles and can calculate newest and optimum parameters. The technology center 40 transmits this newest and optimum vehicle information to the vehicle 10.sub.i, and each vehicle updates the parameters thereof to these newest and optimum parameters. Accordingly, the parameters of the vehicle are set as the newest parameters.