Date: Tue, 24 Sep 1996 13:42:58 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: Tom Sgouros <tomss AT ids DOT net>
Cc: DJ Delorie <dj AT delorie DOT com>, djgpp AT delorie DOT com
Subject: Re: PC Time
In-Reply-To: <Pine.SUN.3.95.960923232748.4132B-100000@conan.ids.net>
Message-Id: <Pine.SUN.3.91.960924133929.11664G-100000@is>
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On Mon, 23 Sep 1996, Tom Sgouros wrote:

> > There is one clock in a PC and it ticks (effectively) 1,193,180 times
> > a second (UCLOCKS_PER_SEC in <time.h>).
> 
> Stupid question, but I have to ask it for clarity: Is this true no matter
> how many MHz your PC is running at?

Short answer:  Yes.

Long answer:  The frequency of the clock which feeds the CPU is lowered to
the above frequency by the chipset on the motherboard.  The CPU itself
gets the original frequency (e.g., 100MHz), but the circuitry that 
generates the timer interrupts gets the above 1.19MHz frequency.  Many 
peripherals and programs will break otherwise.