NCR_SYNCOFF
sr[NCR_SYNCOFF] = 0;
NCR_WRITE_REG(sc, NCR_SYNCOFF, 0);
NCR_WRITE_REG(sc, NCR_SYNCOFF, 0);
NCR_WRITE_REG(sc, NCR_SYNCOFF, 0);
NCR_WRITE_REG(sc, NCR_SYNCOFF, syncoff);