Abstract: A navigation system detects a position of a vehicle, determines an area (i.e., a State) associated with the position of the vehicle, selects and loads a program corresponding to the area for controlling the provision of one or more navigation functions, and navigates the vehicle according to the loaded program. The program is based on a rule as to a navigation that is function enforced in the area in which the vehicle is located.

Abstract: An ECU is equipped with multiple microprocessors. Each microprocessor has an erasable ROM. A communication port of a first microprocessor is connected via an external communication line to a memory overwriter while another communication port of the same microprocessor and a communication port of a second microprocessor are connected to each other via an internal communication line. Before overwriting the contents of the ROM, each microprocessor stores its own identification number whose value is obtained by incrementing the identification number received from the memory overwriter and sending the incremented identification number to the next stage microprocessor. In this way, there is no need to store the identification numbers beforehand in nonerasable memory regions inside the microprocessors.