| 摘要 |
PURPOSE:To speed up DMA by making bus occupation exclusion control by a lower unit itself when the lower unit makes DMA through a common bus in interlace mode. CONSTITUTION:Prior controlling mechanism for lower units-1,-2 is not provided in a C-BUS controlling device 12. Instead of it, the lower unit-1 generates a transfer permission signal TA to the lower unit-2 when the unit-1 itself has no data transfer request. When the unit-1 has data transfer request to the lower unit-2, and received the transfer permission signal TA, outputs a C-BUS occupation request signal REQ, and when the transfer permission signal TA becomes off, completes data transfer in specified time. |
