| 摘要 |
PURPOSE: To smoothly switch the scale of a map being displayed by gradually enlarging or reducing the map to a new scale in a pseudo-executing state based on the currently displayed map data. CONSTITUTION: A CPU 220 reads the scale of a new map stored in a register in an operating section 220. When the reading operation of a new map from a CD-ROM 240 is started, the address of the map data to be read is transmitted to the ROM 240 and, in response to the address, the map data are transmitted to the main RAM 233 of a controller 230. When the map data reading operation is completed, a read requesting flag is reset to '0' and the enlarging and displaying subroutine of the CPU 231 is executed. The subroutine gradually enlarges the map to a new scale in a pseudo-executing state based on the currently displayed map while the map of a newly designated scale is read until the map of the new scale is read and displayed. |
