Date: Mon, 1 May 2000 11:14:39 -0700 (PDT) From: "Rodney W. Grimes" <freebsd@gndrsh.dnsmgr.net> To: dr@dursec.com (Dragos Ruiu) Cc: kpielorz@tdx.co.uk (Karl Pielorz), djb@ifa.au.dk, smp@csn.net (Steve Passe), smp@FreeBSD.ORG Subject: Re: hlt instructions and temperature issues Message-ID: <200005011814.LAA01684@gndrsh.dnsmgr.net> In-Reply-To: <00043018413807.18195@kyxbot.zorg> from Dragos Ruiu at "Apr 30, 2000 06:36:46 pm"
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> On Sun, 30 Apr 2000, Karl Pielorz wrote: > > Taking it to an extreme, it would be like building a system that falls over > > when it 'happens to be busy' one day, 'cause someone ran something > > computationally intensive? - I know for a fact these systems do exist, but we > > don't really want to be helping sweep the cause under the rug do we? > > > > > Tell that to IBM... one of the famous stories from classic computing > history is the mainframe they built with the HCF opcode. > Halt and Catch Fire. It turned out that for this model > you could lock up into a tight one instruction loop and > the CPU core would overheat and literally smoke. > > It's documented in the ancient back issues Mr. Neuman's > old Risks usenet newsgroup in the early eighties. Right along with the chain breaking/hammer bank smoking code for the 1403 printers.... basically a very specific sequence of lines with very special character sequences could cause 1/3 of the hammer bank to fire every 14uS or so, do that for more than 10 cycles or so and you could litterly break the print character chain. De-optimize it for chain breaking and run it for 10 minutes and you would start smoking the hammer coils.... -- Rod Grimes - KD7CAX @ CN85sl - (RWG25) rgrimes@gndrsh.dnsmgr.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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