Third-party DMA uses a system DMA engine resident on the main system board, which has several DMA channels that are available for use by devices. The device relies on the system's DMA engine to perform the data transfers between the device and memory. The driver uses DMA engine routines (see the ddi_dmae(9F) function) to initialize and program the DMA engine. For each DMA data transfer, the driver programs the DMA engine and then gives the device a command to initiate the transfer in cooperation with that engine.