Date: Fri, 30 Oct 1998 17:27:07 -0500 (EST) From: Evan Champion <evanc@synapse.net> To: Warner Losh <imp@village.org> Cc: Evan Champion <evanc@concer.to>, Luigi Rizzo <luigi@FreeBSD.ORG>, Peter Wemm <peter@netplex.com.au>, cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG Subject: Re: cvs commit: src/sys/i386/isa wcd.c Message-ID: <Pine.BSF.4.05.9810301554420.8479-100000@piano.synapse.net> In-Reply-To: <199810301532.IAA21575@harmony.village.org>
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On Fri, 30 Oct 1998, Warner Losh wrote: > K is the prefix for 1024, not Kelvin. m == Milli as a prefix and m == > meters as a unit of measure. This is a common extnetion to SI that > goes back at least 30 years. Actually, I went and looked last night before sending that message out and K is not an official prefix for 2^10. As I said, there is no SI prefix K, and the only legal use of K in SI is for the unit Kelvin. According to <http://physics.nist.gov/cuu/Units/binary.html>, the proposed SI prefixes for binary multiples are: 2^10: kilobinary -> kibi (Ki) 2^20: megabinary -> mebi (Mi) 2^30: gibabinary -> gibi (Gi) 2^40: terabinary -> tebi (Ti) Quoted from that site: "Institute of Electrical and Electronics Engineers (IEEE) Standards Coordinating Committee 14 (SCC 14), Quantities, Units and Letter Symbols, has begun to work with the IEEE Computer Society, the International Organization for Standardization (ISO), and the International Electrotechnical Commission (IEC) to find acceptable names for prefixes that are related to powers of two. A proposal being circulated internationally by the IEC would introduce the new prefixes kibi, mebi, gibi and tebi derived as short unions of the SI prefixes with the word "binary." The proposed new prefix symbols are Ki, Mi, Gi, and Ti. Thus we would have a gibibyte of 2^30 bytes and a gigabyte of 10^9 bytes, and the 90 mm (3 1/2 inch) diskette would be formatted for 1440 KiB." I'm not suggesting that all the units be fixed (I can just imagine the stream of users asking "What the hell is a KiB/s?" :-); I just wanted to note that KB is a ficticious unit. Evan To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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