| 摘要 |
In a display memory 10, a display data storage area designation register 11 designates a display data storage area, and a mask bit width designation register 12 designates a write mask bit width. According to certain data provided by address parameters of a re-writable memory, the display data storage area designation register, and the mask bit width designation register, a mask control signal generator 13 provides a mask control signal for an external address data to a write control unit 14. The mask control signal is generated from a set of comparisons based on the width of the re-writable memory and the mask bit width to determine what data in the memory may be re-written. The write control unit 14 writes only certain bits of external write data into the display memory 10.
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