RTC (DS1307 or other) with millisecond resolution

robtillaart:
why not use an 5 hour scale for 12 hours ??????

5 hours day, 5 hours night ??

Well, that's how it's supposed to work... but what I meant was that they were taking a standard analog 12-hour clock where one rotation of the hour hand is always 12 hours and slapping a face on it that only shows 10 hours. But since they didn't changing the timekeeping of the clock it self, it still takes 12 real hours to traverse their version of 10 metric hours. You are absolutely right of how it's really done, my point was that those are a mere novelty and not correctly representative of metric time.