@MelissaBearTrix @davidtheeviloverlord @chu To add on to this, quartz has piezo electric qualities. If you strike it, it generates a charge, but if you run a charge through it it bends, completing a circuit. If you take particularly pure quartz, and shape it very precisely, you can make a highly accurate clock circuit, pretty much the most accurate you can get short of using atomic clocks. During WW2 quartz crystals were considered a military secret by the british, as they were used to tune their radios (for radar, etc). Early computers used them extensively, highest I ever saw was 33Mhz.

By writing "quartz" on the watch, they're advertising that it's pretty damn accurate. Compared to pre-quartz based time measurement.

I know modern devices use MEMS devices -- essentially a very tiny tuning fork made on a silicon chip -- for their low frequency clocks (ballpark of 15khz, the standby clock in a phone will use this), I'm not sure how the 100Mhz + signals are made

@sophie @chu @davidtheeviloverlord @MelissaBearTrix I think 33 Mhz is the max they can naturally ocsillate under their own energy or something like that. But the quartz clocks in computers is why early machines had just these wacky clock speeds like 18.333 Mhz, but I remember reading an article saying that thise old IBM mainframes kept time more accurately than modern machines do.

@praetor above ~30MHz one generally uses so called PLLs or phase locked loops. It kinda works the same as with a quartz where you oscillate at 32767 times per second and count to 2**15 and you finish counting in 1.00000 seconds, but here you start with a digital oscillator at say 4.3 GHz and divide by counting till say 2**16 (about 65536) , and then compare that pulse with a quartz clock or MEMS clock that accurately runs in the high kHz range (say 65kHz for a 4.3GHz system), and you speed up or slow down your 4.3GHz thing depending how much too late or too early you finished counting.
@sophie @chu @davidtheeviloverlord @MelissaBearTrix