3 ms·
It kinda makes you wonder why desktop computers don't use the AC frequency as a stable-ish time source. Short-term accuracy is pretty poor, but it can definitel
by crote 3y ago
It kinda makes you wonder why desktop computers don't use the AC frequency as a stable-ish time source. Short-term accuracy is pretty poor, but it can definitely do better than 12 seconds over a week!
- moffkalast 3y agoI suppose it's because no AC ever gets to the motherboard in your typical ATX setup? It's all just DC 12/5/3 volts and could be coming from a battery for all it knows. There would need to be an optional standard way of getting time from the PSU and have the AC time keeping there.
- crote 3y agoOf course, but there's no reason why a 50/60Hz signal couldn't have been included in the ATX power connector back when it was established a few decades ago. In an alternate universe it would've been put in there, together with all the weird -12V / -5V rails nobody uses these days. Getting it these days would indeed be pretty much impossible.
- labcomputer 3y agoSure, but it costs extra and nobody (to a first approximation) cares. So why bother?
- brohee 3y agoThat's a very optimistic assumption, the target is 50Hz but if it is below or over for a long period of time (e.g. high load in winter making it hard to sustain the nominal frequency) there are no provision to make it run faster or slower unless the time drifted by more than 30s (that's possibly only valid for Europe). More at https://wwwhome.ewi.utwente.nl/~ptdeboer/misc/mains.html https://wwwhome.ewi.utwente.nl/~ptdeboer/misc/mains.html
- calfuris 3y agoThe standards are tighter in the US, with corrections being triggered by 10/3/2s differences and stopping at 6/0.5/0.5s (Eastern/Texas/Western interconnections). Src: https://www.naesb.org/pdf2/weq_bklet_011505_tec_mc.pdf https://www.naesb.org/pdf2/weq_bklet_011505_tec_mc.pdf