| 摘要 |
<p>A graphic board can be inserted into the expansion slot of a computer and, when a value is set in a register from the computer side, the frequencies of horizontal and vertical synchronizing signals can be set precisely. At the time of starting display, the display is performed at the synchronizing frequency corresponding to the display of 640 dots by 400 lines normally designed to a CRT display device (step S100). Thereafter, the synchronizing frequency is gradually raised to the target value corresponding to the display of 640 dots x 480 lines (steps S120 to S140). While the synchronizing frequency is raised, the CRT display device is continuously synchronized despite the deviation of the frequency within a tolerance range, because its internal synchronous circuit operates. As a result, the CRT display device is maintained in the synchronized state until the target value is reached and the display of 640 dots by 480 lines becomes possible. <IMAGE></p> |
