Map data processing unit

A map data processing unit that has a function of updating map data, and includes a display section for performing various types of display including display of a processing result of the map data, a manipulation section for carrying out input manipulation for processing the map data, and a control section for performing entire control, said map data processing unit comprising:

• a post-update data cache section for temporarily storing, in a cache, latest version map data to be read in response to a request for map data;
• an update data input section for inputting update data for updating the map data to the latest version map data, when said post-update data cache section does not store the map data;
• and
• a dynamic update section for updating, when said update data input section inputs the update data, old version map data to latest version map data to be stored in the cache, in accordance with the update data fed from said update data input section every time a request for the map data occurs;
• a pre-update section for updating a plurality of map data in advance;
• a pre-update decision section for deciding the map data to be updated in advance by said pre-update section;
• and
• a pre-update data recording section for recording the map data that is updated by said pre-update section and is to be read in response to the request for the map data.