Date: Wed, 22 Sep 1999 20:09:08 +0200 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: jbryant@tfs.net Cc: green@FreeBSD.ORG (Brian F. Feldman), freebsd-current@FreeBSD.ORG Subject: Re: Testers please! Message-ID: <34758.938023748@critter.freebsd.dk> In-Reply-To: Your message of "Wed, 22 Sep 1999 10:25:27 CDT." <199909221525.KAA28026@argus.tfs.net>
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In message <199909221525.KAA28026@argus.tfs.net>, Jim Bryant writes: >since there is only a single master clock oscillator, there really >should be no frequency difference between CPUs. As long it runs constantly: yes. As soon as you have clock-stop events you will have different resync times for the on-chip PLLs. >Ideally, motherboards should be >designed to have equal length clock lines to each CPU, They are, but that doesn't mean that the PLL'ed core frequencies are in lockstep when the clocks change. >the current price of accurate TCXOs is low enough to be economical in >PCs, and these seriously reduce the drift compared to the cheezy TTL >clocks currently used. There are no cheesy TTL clocks used. There are random encapsulated rock with pretty high-quality drive circuitry and PLL generation of all sorts of other frequencies. >speaking of atomic breakdown... they could start making cheaper >cesium-beam tubes given the current level of the nuclear waste issue The actual amount of Cs in the Cesium unit has no cost impact. There are man components of a Cs unit which carry significantly higher pricetags than the few grammes of Cs. A un-optimally constructed Cs is worse than a low-cost Rb unit. >Cesium beam tubes are essentially extremely accurate >narrow bandwidth filters, and not oscillators. It is neither. >with russia having made two seperate threats of aggression to destroy >the entire planet with nuclear weapons in the past twelve months [...] Lets not get too far from the topic, OK ? -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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