TX39_INTRENABLE8_REG
tx_conf_write(tc, TX39_INTRENABLE8_REG, 0);
iregs[8] = tx_conf_read(tc, TX39_INTRENABLE8_REG);
tx_conf_write(tc, TX39_INTRENABLE8_REG, 0);
tx_conf_write(tc, TX39_INTRENABLE8_REG, iregs[8]);