Melanie thanks for your response.

I have used a number of 1-wire devices and iButtons in the past.
So reading from and writing to the DS1994 is no problem.

The "Time" reading from the DS1994 is a 5 Byte value
that contains the number of seconds (and fractional seconds) elapsed since the counter has been started.

The least significant of those 5 bytes contains fractional seconds.
So we actually have only to deal with a four bytes (or Dword) seconds counter.

To set the Clock choose a reference date, calculate the number of seconds that have elapsed from then til "NOW" and write this to the DS1994 as the "start-value"

All this works fine and the clock is running.

But how do I calculate Year, Month, Day, Day of Week and Time from that DWord Counter to have something more readable to display having only the poor integer math of the PIC?

Best regards

Ralph