Date: Wed, 24 Dec 1997 00:56:16 -0500 (EST) From: Peter Dufault <dufault@hda.com> To: hasty@rah.star-gate.com (Amancio Hasty) Cc: hackers@FreeBSD.ORG Subject: Re: procedure to adjust clock drift? Message-ID: <199712240556.AAA23306@hda.hda.com> In-Reply-To: <199712241826.KAA01767@rah.star-gate.com> from Amancio Hasty at "Dec 24, 97 10:26:56 am"
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> I was told that PCs clocks are usually reliable and they are usually > off by a fixed clock offset so yes I am thinking about adjusting > the frequency on the clock in my PC. Typically, I use ASUS motherboards > which come equip with a Dallas Semiconductor RTC which is supposed > to be good. Guess, I have to go to the Dallas Semiconductor web site > to find out more about my RTC part. You'll find the specs will show that being off a few seconds per day is OK. > > > > I wrote some time ago a driver which connects a cheap DCF clock > > (german radio standard time signal (others should be easy to implement) > > controlled, price at about 10-20 $) via a simple interface to my > > (otherwise unused :-) game port (iX 11/1994p6). > > Oh, that sounds great most time clocks run about $1000 or so around > here . I wonder if there is a US counterpart. I think you're mixing synchronization cards that provide highly accurate time sync between multiple systems with one that picks up a radio broadcast. The sync cards have one master optionally with a satellite hookup and multiple slaves. The clocks that pick up the NIST radio signal in the US are only about $60.00 or so. I saw one in the last "Damark" catalog. I even saw a nice looking analog one for about $120.00. Apparently the PBS TV stations also broadcast the time in the US - I got a VCR as a gift and when I plugged it in first time it said something like "searching for PBS time signal..." and then set the clock. That should be right up your alley and of course you already have a TV tuner in your computer. Peter -- Peter Dufault (dufault@hda.com) Realtime development, Machine control, HD Associates, Inc. Safety critical systems, Agency approval
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