| 摘要 |
PURPOSE:To detect a character position efficiently by calculating a display controlled area on the basis of the number of display characters which corresponds to variance due to the response speed of a pen device, erasing data in the area and displaying characters, one by one, and detecting its display position by an interruption. CONSTITUTION:A CRT controller 1 stores a current refresh memory address by a light pen strobe signal obtained through a light pen interface device 9. Then, a processor 11 obtains the refresh memory address by the device 1 to calculate a display character area to be brought under display control on the basis of the number of display characters which corresponds to variance due to the response speed of a light pen 7. The contents of the obtained character display area are erased and then characters are displayed, one by one, in the area; and an interruption is detected to detect the light pen position. |
