VR_CLRBIT16
VR_CLRBIT16(sc, VR_COMMAND, (VR_CMD_RX_ON|VR_CMD_TX_ON));
VR_CLRBIT16(sc, VR_COMMAND,
VR_CLRBIT16(sc, VR_COMMAND, VR_CMD_FULLDUPLEX);
VR_CLRBIT16(sc, VR_COMMAND, (VR_CMD_TX_ON|VR_CMD_RX_ON));
VR_CLRBIT16(sc, VR_COMMAND, VR_CMD_RX_ON);