The MA31753 Direct Memory Access Controller (DMAC) is a peripheral interface circuit design primarily for use with the MA31750 microprocessor. Each DMAC provides up to four independant, prioritised channels each of which can perform DMA transfers between memory and/or I/O devices using the MA31750 bus. Each channel has its own programmable internal priority and can be masked under program control. Further, individual channels have their own associated status and control words enabling an individual channel to be reprogrammed without disturbing transfers which may be taking place on other channels. Three basic transfer modes are available: