| 摘要 |
<p>PURPOSE:To improve the performance of a CRT display device by transferring a screen image of a transfer unit changed in a logical screen memory via a DMA control part based on the transfer corresponding information on a table memory corresponding to the output transfer unit of a rewrite detecting circuit. CONSTITUTION:The software functions to calculate the transfer address relation between a logical screen memory 11 and a display screen memory 13 and registers this calculated relation into a table memory 16. Then the address areas whose logical windows are stored in the memory 11 are registered in a rewrite detecting circuit 15. Hereafter the circuit 15 detects a specific logical window that includes the relevant rewritten address in case the contents of the memory 11 are rewritten. Then the circuit 15 gives an instruction to a DMA control part 12 for start of the transfer of an area. Then the part 12 decides a specific area to be transferred from the information received from the circuit 15 and the contents the memory 16 corresponding to said information. Thus the transfer of data is carried out.</p> |
