This was due to a slight dip in the mains frequency. That dip didn’t put anything out of commission, but clocks that are designed to accumulate the total zero-crossings of the power grid ...

A while back we saw a logic clock ... test the LED array version(); // Display the version number of the software displaytime(); // display the current time TMR1H=0xff; TMR1L=MAINS_DLY; // reset ...