ATA_BM_COMMAND_START_STOP
command = *channel->bm_command_reg | ATA_BM_COMMAND_START_STOP;
*channel->bm_command_reg = command & ~ATA_BM_COMMAND_START_STOP;
command |= ATA_BM_COMMAND_START_STOP;
command & ~ATA_BM_COMMAND_START_STOP);