Message-Id: <m10XtJx-000S8dC@inti.gov.ar>
Comments: Authenticated sender is <salvador AT natacha DOT inti DOT gov DOT ar>
From: "Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
Organization: INTI
To: Adam Schrotenboer <ajschrotenboer AT lycosmail DOT com>, djgpp AT delorie DOT com
Date: Thu, 15 Apr 1999 18:10:07 +0000
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Subject: Re: UCLOCK_PER_SEC value
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Adam Schrotenboer <ajschrotenboer AT lycosmail DOT com> asked:

> I noticed that in time.h UCLOCKS_PER_SEC is defined as 1193180, but when
> I take 2^32/3600 i get approximately 1193046. I know that this isn't
> much difference, only 134, but was still wondering why this is.

That's because no power of 2 is involved, original PCs (from IBM) had a 
14.31818 crystal for:

1) fc/3=4.7727 = CPU clock
2) fc/4=3.579545 = color subcarrier for NTSC (yes TV output!)
3) fc/12=1.193181667 = clock for the timer (3 timers in one chip).

SET

P.S. All in MHz

 
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