[time-nuts] 4.19 MHz xtal

[ed breya]

Your crystal doesn't show enough digits to see why it's a common value. 
The "exact" number should be 4.194304 MHz, which is 2^22. It can be 
divided by this base-2 integer conveniently to make 1 Hz for clock use. 
The crystal marking, especially on small, common parts is often rounded 
or truncated, but users know what it's supposed to be. If you see "3.58" 
on a crystal in a NTSC TV set, you know the right digits to six places 
if you're familiar with the use.

Ed