| 摘要 |
PROBLEM TO BE SOLVED: To eliminate the situation in which unnecessary accesses are conducted to a video memory and a display buffer because image data, that are overwritten by an attribute having a higher display priority and are not displayed, are read from the video memory and being written into the display buffer. SOLUTION: The device is provided with an attribute converting circuit and a source address computing circuit. When display regions of attribute data on a prescribed horizontal one line of a display screen are overlapped, the pixels of an attribute having a lower display priority are disappeared and the display regions on the screen are changed by the disappeared pixels, the changed display regions are made into new display regions by the attribute conversion circuit. If divided, the attribute data are converted into attributes having the number of divisions in which divided display regions are made into new display regions by the attribute converting. The source address computing circuit computes addresses of a video memory, in which corresponding source image data exist, from new display regions converted by the attribute converting circuit. Note that the operation, in which data in the video memory are written into a display buffer for every horizontal display line, is repeatedly conducted.
|
