| 摘要 |
<p>PURPOSE:To secure the overlap checking for the regions already decided in a short time by memorizing the decision bit indicating whether the display position on the screen is used or not and then setting the decision bit under the using state in accordance with the region already displayed. CONSTITUTION:Screen buffer 10 is composed of m-row and n-column units of unit memory 11 comprising part 11a memorizing the character codes and decision bit 11b indicating whether the display position on the screen is used or not. The information sent from data input part 23 is sent to display screen control part 22 via display control part 21. At part 22 an operation is given to the address corresponding to the display information, and the decision bits corresponding to the display position and its adjacent display positions which correspond to the wiriting positions of buffer 10 are extracted. Whether the decision bit indicates the using mode or not is decided at flag decision part 20, and the decision result is informed to part 22. And is case the desicion bit indicates the using mode, the information of buffer 10 corresponding to the region already displayed is erased. Then the region which is not used yet is looked for to write the necessary information there, thus the using mode is secured for the decision bit.</p> |
