| 摘要 |
<p>PURPOSE:To decrease the load of a CPU and to improve operability by adding a function to operate a plotting address by the result of an address comparison to a clipping function which controls the address comparison and possibility of plotting. CONSTITUTION:The previously assigned clipping region of a memory by comparators 7a to 7d is subjected to the comparison of the boundary address and plotting address by using a data transfer device which transfers the rectangular data of the size assigned from the CPU for the display memory to the assigned memory position and selectors 9a, 9b are controlled according to the result of the comparison to change the selection of the plotting address. Then, the additional function of the clipping that the data transfer device can make address comparison and adjustment of the plotting address with hardware without the aid of the software processing of the CPU is obtd. The load of the CPU processing is decreased in this way and the operability is improved.</p> |
