| 摘要 |
<p>A device for processing map data. A first data unit corresponds to a map of a desired area, and a second data unit corresponds to a map of a partial area of the desired area. The first and second data units are stored on a data storage device. A controller is operable to update the second data unit, to partially update the first data unit by storing the updated second data unit in the first data unit and to store the partially updated first data unit in the data storage device.</p> |
