PURPOSE: To speed up a retrieval for map information right after a system is powered on by storing priority information indicating area information in use in a nonvolatile storage means.
CONSTITUTION: A microcomputer(MPU) in an electronic controller ECU is equipped with a small-capacity RAM internally and a backup battery is provided to a power source part so that data on the RAM are not erased. Then data specifying the area information used for the calculation and display of a position if stored in the nonvolatile RAM as priority information and when the area information to be used is altered, the priority information on the nonvolatile memory RAM is also updated into the latest one. Therefore, when the device is powered off and then on again, the priority information indicating the area information which is used last is stored in the nonvolatile RAM. Consequently, the best area information can be retrieved instantaneously without retrieving other areas.
IWADE SHIGERU
YAMAMOTO TOMOHIRO
