| 摘要 |
PURPOSE:To search for map data on a new area instantaneously when a current position deviates from the range of a map being selected by making area information, provided corresponding to each page of the map, contain adjacent map data numbers adjoining to the area. CONSTITUTION:An arithmetic board in an electronic controller ECU is equipped with a microcomputer(MPU), a ROM, and a RAM, and the ROM is stored with the area information corresponding to the map previously. Then the area information provided corresponding to each page of the map contains the presence positions (e.g. pages of the map) of pieces of area information of adjacent areas at the right, right upper, upper, left upper, left, left lower, lower, and right lower positions about the area on the map. Therefore, if the current position moves out of the area to the north side, an adjacent map is retrieved by utilizing 'upper' adjacence information and when the current information is included in it, the map is used thereafter. Consequently, a large amount of data need not be retrieved each time the current position moves out of one area. |
