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From: bryce@hoser.berkeley.edu (Bryce Nesbitt)
Newsgroups: comp.sys.amiga
Subject: Re: Problems with the Real Time Clock on my Amiga 2000
Message-ID: <21572@ucbvax.BERKELEY.EDU>
Date: Tue, 3-Nov-87 01:31:25 EST
Article-I.D.: ucbvax.21572
Posted: Tue Nov  3 01:31:25 1987
Date-Received: Fri, 6-Nov-87 22:48:02 EST
References: <17259@amdahl.amdahl.com> <552@esunix.UUCP>
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Organization: University of California at Berkeley
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In article <552@esunix.UUCP> blgardne@esunix.UUCP (Blaine Gardner) writes:
>in article <17259@amdahl.amdahl.com>, kim@amdahl.amdahl.com (Kim DeVaughn) says:
> 
>< It's easy to fix though ... there is a small trimmer capacitor just about
>< directly to the front of the 86-pin coprocessor slot, very near to the
>< Oki clock/calendar chip, that you can adjust.  On my machine, it was a
>< bright yellow color.
>
>There has GOT to be a better way! George, Dave, anybody, if I've got an
>oscilloscope (and an A2000 of course :-) where do I look, and for what
>signal?

Anybody here:

Pin 1 of the OKI MSM6242B can be used for calibration.  Hook a scope
to it (better yet, a frequency counter).
You will probably see something close to:

1/64th second
1 second
1 minute
1 hour
-or-
something strange (in the neighborhood)

It will probably be near 1/64th.  Adjust until it is exact.  (Beware
that temperature affects crystals).
If it is *not* at 1/64th of a second, register $E needs to be set
to zero.  This falls in the category of "magic" unless you have
the docs for the chip or perhaphs the A500/A2000 tech. ref.


BTW: I got an answer from comp.sources.amiga.  Perhaphs there is
life after all!

|\ /|  . Ack! (NAK, SOH, EOT)
{o O} . bryce@hoser.berkeley.EDU -or- ucbvax!hoser!bryce
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