CMD_DMA_MODE
writeb(CMD_NOP + CMD_DMA_MODE, ®s->command);
writeb(CMD_NOP + CMD_DMA_MODE, ®s->command);
writeb(CMD_DMA_MODE + CMD_NOP, ®s->command);
writeb(CMD_DMA_MODE + CMD_XFER_DATA, ®s->command);
writeb(CMD_DMA_MODE + CMD_NOP, ®s->command);
writeb(CMD_DMA_MODE + CMD_XFER_DATA, ®s->command);