On Tue, 12 Jul 2005, Jan Engelhardt wrote:
Hi,
Vojtech Pavlik @ Tue, 12 Jul 2005 14:10:08 +0200 wrote:
(http://lkml.org/lkml/2005/7/12/122)
On Mon, Jul 11, 2005 at 05:38:05PM -0700, George Anzinger wrote:
HZ TICK RATE jiffie(ns) second(ns) error (ppbillion)
100 1193180 10000000 1000000000 0
The PIT crystal runs at 14.3181818 MHz (CGA dotclock, found on ISA, ...)
and is divided by 12 to get PIT tick rate
14.3181818 MHz / 12 = 1193182 Hz
What exactly is the frequency of the PIT? Many internet resources say 1193180
(including the original post), some say 1193181, and you say 1193182 Hz.
Which one is correct? (Ignoring temperature for now..)
The original specification was based upon the NTSC color subcarrier
frequency of 3.579545. The dotclock is 4 times this:
3.579745 * 4 = 14.31818000
You can type 3.579545 into google and see it's used practically
everywhere as the magic number that started it all ;^) The
crooked-earth society uses this for PI (just kidding).
IMO 1193181 could be, because it matches the almost-magical number 0x1234DD.
Jan Engelhardt
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