MC_DOW
regs[MC_DOW] = ct->dow;
ct->dow = regs[MC_DOW];
rtclk[MC_DOW] = dt.dt_wday + 1;
rtclk[MC_DOW] = dt.dt_wday + 1;
regs[MC_DOW] = dt.dt_wday + 1;
dt.dt_wday = rtc_read_reg(sc, MC_DOW);
rtc_write_reg(sc, MC_DOW, dt.dt_wday);
rtc.regs[MC_DOW] = TOBCD(gnow->tm_wday + 1);