| 摘要 |
PURPOSE:To simplify a plotting processing and to execute a processing at a high speed by dividing virtually a graphic plotting address, and not executing a decision and the change of a segment value in the course of plotting. CONSTITUTION:A display screen of a CRT is divided into three so as to become virtually almost the same size. Subsequently, segment values required for designating the head address of each area 21-23 by an offset value zero are denoted as S1, S2 and S3. In such a state, the Y coordinate in a position of a graphic is checked, and when it is smaller than a start position L2 of a second area 22, the segment value is set as S1 (step 42). When it is smaller than a start position L3 of a third area 23, the segment value is set as S2 (step 44). When it is in a third area 23, the segment value is set as S3 (step 45). Next, while changing an offset value to a graphic memory with respect to a pattern of the graphic along the X coordinate of the graphic, an image of a height portion of the graphic is copied. In such a way, plotting of the graphic can be executed without executing offset monitoring, and a change of an offset value in the course of plotting. |
