Upgrade for navigation data based on usage data or initialization of navigation data

摘要

An upgrade method for navigation data is provided with: a memory status of a memory device that is removed from a navigation apparatus is checked and it is determined whether there are the navigation data to be upgraded and the user data to be saved. The user data is saved in a backup memory device. The navigation data is written over with upgraded navigation data. Then, the saved data is read from the backup memory device and rewritten in the memory device as the user data.