New ask Hacker News story: Ask HN: Is a 1Mhz CPU precisely 1Mhz? How are clock crystals so accurate?

Ask HN: Is a 1Mhz CPU precisely 1Mhz? How are clock crystals so accurate?
2 by andrewstuart | 2 comments on Hacker News.
When programming something timing dependent it is often necessary to very precisely time things. So I'm wondering if the system clock really is precisely the megahertz advertised? And if so, how are crystals made so precise?