Hacker News Reader

Air-gapped and automatically handles DST correctly seems like a small niche to me, but I'd be happy to be proven wrong.

View on HN

Anything safety critical with strict reporting requirements (clock must be correct so logs are accurate).

Honestly, most things that need to be air-gapped also need to have correct clocks. Most other things also need to have correct clocks / time, but it is easier to use available stuff in that situation.

industrial control systems, medical devices, transportation systems, important, critical infrastructure stuff.

Okay, I have to ask: shouldn’t a system like this use TAI or at least UTC? If you are air gapped and really need accurate time, you at least have to deal with leap seconds. Even if a one-second error doesn’t bother you, there’s an entire two-hour interval when DST ends in which the local time is ambiguous. Or do these systems try to do the right thing by distinguishing 2:30 AM PST from 2:30 AM PDT?

Sure, internally you will store it in something less ambiguous... but you still have to display the correct time & timezone and be able to set the time correctly (and note when the clock has been set). Time is generally set by humans according to their local time. So you do need to differentiate PST from PDT, even if something like that is kind of an edge case..

Reply on news.ycombinator.com