From owner-freebsd-hackers Wed Dec 24 15:33:31 1997 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.7/8.8.7) id PAA09132 for hackers-outgoing; Wed, 24 Dec 1997 15:33:31 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from ghost.mep.ruhr-uni-bochum.de (ghost.mep.ruhr-uni-bochum.de [134.147.6.33]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id PAA09123 for ; Wed, 24 Dec 1997 15:33:23 -0800 (PST) (envelope-from roberte@ghost.mep.ruhr-uni-bochum.de) Received: (from roberte@localhost) by ghost.mep.ruhr-uni-bochum.de (8.8.5/8.8.4) id AAA17532; Thu, 25 Dec 1997 00:33:11 +0100 (MEZ) From: Robert Eckardt Message-Id: <199712242333.AAA17532@ghost.mep.ruhr-uni-bochum.de> Subject: Re: procedure to adjust clock drift? In-Reply-To: <199712241755.LAA09424@unix.tfs.net> from Jim Bryant at "Dec 24, 97 11:55:49 am" To: jbryant@unix.tfs.net Date: Thu, 25 Dec 1997 00:33:11 +0100 (MEZ) Cc: freebsd-hackers@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL31H (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk It was Jim Bryant who wrote: > if you are adventurous, you can tweak the loading capacitor for the > clock crystal.. to zero the clock to the design frequency. best way > to do this is to get a frequency counter and monitor the output of the > oscillator while tweaking the capacitor [the variable near the > crystal]. if you don't have a counter, the next best way to do this > is to try trial and error by ear using some known reference such as > WWV. to get a properly adjusted oscillator, you can spend upwards of > a month using the trial and error method, as only cumulative error > will be noticable. use a counter if you can find one!B I think most motherboards nowadays use integrated oscillators without any tuneable parts -- at least I found none on my motherboards. My old 486-board stayed about 4 s/d behind when powered off and went 8 s/d ahead when in use. The ASUS I have now for my Pentium goes about 1 s/week behind. (I tuned my watch to 10 s/a, but now it's sensitive to the battery voltage.) > this can be alleviated by running xntpd or timed, which by getting the > time from a stratum 1 timeserver at regular intervals can skew the > clock via software to correct for the frequency error of the > oscillator. I agree, if you have a (permanent) connection to the internet this is the way I would go, but not all systems have one. Robert -- Robert Eckardt \\ FreeBSD -- solutions for a large universe.(tm) RobertE@MEP.Ruhr-Uni-Bochum.de \\ What do you want to boot tomorrow ?(tm) http://WWW.MEP.Ruhr-Uni-Bochum.de/~roberte For PGP-key finger roberte@gluon.MEP.Ruhr-Uni-Bochum.de