| 摘要 |
PURPOSE:To prevent the performance of a system from being lowered by evading the occupancy of a system bus by a DMA controller at the time of transferring a data to a laser beam printer, by using a dual port memory as a printer image buffer. CONSTITUTION:An interface circuit is constituted of the dual port memory 15, and a function as the buffer memory of the laser beam printer is provided. In such a way, by operating the circuit asynchronously with the transfer rate of the laser beam printer, and also, enabling the content of the dual port memory 15 to be updated even during a time of outputting the data to the laser beam printer, the occupancy of the system bus 6 by the DMA controller 14 for a long time can be evaded at the time of transferring a DMA data from an image memory 3 to the dual port memory 15. |
