COMPLETE_DMA_SCB_HEAD
comp_head = ahd_inw(ahd, COMPLETE_DMA_SCB_HEAD);
ahd_outw(ahd, COMPLETE_DMA_SCB_HEAD, scbid);
scbid = ahd_inw(ahd, COMPLETE_DMA_SCB_HEAD);
ahd_outw(ahd, COMPLETE_DMA_SCB_HEAD, SCB_LIST_NULL);
ahd_outw(ahd, COMPLETE_DMA_SCB_HEAD, SCB_LIST_NULL);
scb_index = ahd_inw(ahd, COMPLETE_DMA_SCB_HEAD);