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Mail Archives: djgpp/2000/10/13/09:02:35

From: gdemont AT my-deja DOT com
Newsgroups: comp.os.msdos.djgpp
Subject: Re: Fine timing
Date: Fri, 13 Oct 2000 12:17:11 GMT
Organization: Deja.com - Before you buy.
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References: <8s4ini$g3i$1 AT nnrp1 DOT deja DOT com> <7458-Thu12Oct2000175507+0300-eliz AT is DOT elta DOT co DOT il>
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To: djgpp AT delorie DOT com
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Reply-To: djgpp AT delorie DOT com

> > A small question: is a "middle" frequency timer
> > available from djgpp run-time (say ~1Khz, i.e. a bit
> > more than the 18.2 Hz of DOS)

Eli:

> Did you consider the CMOS real-time-clock timer?  It runs at 1024Hz by
> default and triggers Int 70h on IRQ8 (IIRC).

By default ? This is very good news!!

> By default, this clock's
> interrupt is disabled, but you can enable it by writing appropriate
> values into port 70h.

Nice! And is it possible to read the 1024ths of second from port 70h
without using an interrupt ? In that case it would simplify dramatically
things. For the moment I program the PIT, take Int 8 and repair the BIOS
time that would go wrong otherwise by reading the values from port 70h!
I works, but is not so nice and needs not forgetting to reset the
normal state a the end - especially when an unhandled Ada exception
has occured.
Anyway, thank you very much, I'll see on that side!

Gautier


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