| 摘要 |
PURPOSE: To make image data previously prepared reusable without disturbing plotting actions by providing an image data storage section which reads and stores image data for reuse when erasing the image data accessed by a plotting section and stored in a frame memory. CONSTITUTION: Read-out of image data from the frame memory 5 by a plotting section 3 and its transfer to an image data storage section 4 are simultaneously carried out when the plotting section 3 receives the instruction of erasing the frame memory 5. Through this, when the frame memory 5 is erased, that is, when the renewal of image data on the frame memory is required on the frame memory 5, the image data to be discarded is transferred to the image data storage section to be stored, and thereby it is no longer required to execute the command that the CPU 1 directly reads the image data from the frame memory 5 for reuse. And the time to restrict the frame memory 5 is shortened, minimizing the time during which plotting to the frame memory 5 is restricted. |
