DATA UPDATING SYSTEM FOR DISPLAY MEMORY

PURPOSE: To prevent flickering of display in a display screen especially in the case that the speed at which data is written in a display memory is higher than the period of one-frame raster scanning by displaying rewritten display data at least once. CONSTITUTION: A latch circuit 11 holds a plottin...

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1. Verfasser: YASUMURO TAKETOSHI
Format: Patent
Sprache:eng
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Zusammenfassung:PURPOSE: To prevent flickering of display in a display screen especially in the case that the speed at which data is written in a display memory is higher than the period of one-frame raster scanning by displaying rewritten display data at least once. CONSTITUTION: A latch circuit 11 holds a plotting address, that a plotting processor 6 sends to a bit map memory 9, and holds the last plotting address of a series of display data rewritten by the plotting processor 6. A comparison circuit 12 compares the address held in the latch circuit 11 with a display address for read of display data, which is sent from a CRT control circuit 7, and sends a coincidence signal in the case of coincidence. A counter 13 counts the signal sent from the comparison circuit 12, and when the counted number reaches a prescribed value, the counter sends a signal to the plotting processor 6 so that it will start the write processing of a series of next display data. Consequently, rewritten blocks are certainly displayed even if the plotting speed at which display blocks are expanded in the display memory is high. Thus, flickering of the picture is prevented.