Many pendulum clocks are capable of well under 1 ppm accuracy, which is better than many quartz oscillators. Here is a tour of clock precision by orders of magnitude:
That's correct. On NT/Alpha context switching was done in ntos\ke\alpha\ctxsw.s, which was regular kernel mode assembler code. A PAL call was made but it simply set the new Teb and Pdr; two or three lines of code. I've never seen the PALcode for VMS or OSF/Tru64 but the NT PAL for swpctx was designed so that alpha assembler code in NT looked as much like the mips code that davec wrote. It made the port easier that way.
Interesting Raymond continues to mention NT/Alpha now and then. If you run into him mention I have a collection of NT/Alpha artifacts and anecdotes he might be interested in.
That's the price -- when new. But most "time nuts" buy their atomic clocks well used on eBay or local surplus sales at a massive discount. For example the most recent H-maser on the hobbyist market went for just a few thousand. Granted it was in need of repair, but that journey is part of the fun of an atomic timekeeping at home hobby.
Author of the web site (leapsecond.com) here if you have any questions. I don't know how the title of the HN post was chosen. The actual title of the web page is "GPS, UTC, and TAI Clocks".
The page is a javascript animation of "GPS system time", UTC, and TAI showing how they all tick together but are offset from each other by an integer number of seconds. It's a fixed integer in the case of TAI and GPS and a variable integer in the case of UTC.
TAI and UTC are based on the SI second. The SI second is specifically defined in terms of cesium atoms at no temperature, no velocity, and no elevation (aka, on the geoid). Consequently TAI and UTC are immune from relativistic effects, by definition.
On the other hand, the physical clocks in the laboratory are not immune and that's why they have to be corrected for a dozen factors, the largest of which is usually gravitational redshift. To appreciate the complexity and precision of this correction see this NIST paper:
You can grep the web for Dik's original version. The 3-line homage version I linked contains both his full name and the name of the algorithm used: "spigot" (as in spew, faucet), which itself contains the letters PI. In addition, this version outputs exactly 31416 digits of pi. So it's triple self-referential. Happy 2022.03.14 pi day to all.
http://leapsecond.com/ten/
Here is a world record setting pendulum clock from a few years ago:
http://leapsecond.com/pend/clockb/
Precision pendulum clocks are a very deep rabbit hole.