Date: Thu, 21 Feb 2002 16:59:06 +1100 From: Michael Wardle <michael.wardle@adacel.com> To: "Gary W. Swearingen" <swear@blarg.net> Cc: doc@FreeBSD.org Subject: Re: inconsistent use of data units Message-ID: <3C748CAA.9060805@adacel.com> References: <3C743707.3080505@adacel.com> <20020221003116.GA11893@hades.hell.gr> <3C744D39.1020308@adacel.com> <1014256250.304.66.camel@cocaine> <3C745639.8080509@adacel.com> <3C7463A5.5060204@pittgoth.com> <3C74673E.8010905@adacel.com> <4r664rbe2u.64r@localhost.localdomain>
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Gary W. Swearingen wrote: > Michael Wardle <michael.wardle@adacel.com> writes: > > >>If computer scientists had wanted to define their own units for >>computing, then they so be it. In adopting the SI prefixes (K, M, ...), >>however, there was an implied decision to make computing units defacto >>SI units. >> > > Does that mean they decided that "bytes" were SI units and that kBytes > should mean 1000 bytes? Obviously, the used a non-SI factor of 1024 > and I thing the implication (the inference anyway) would be that "bytes" > are NOT SI units as the prefixes are not. They just share the same > names, unfortunately. No, the decision was made when the K, M, G, etc. prefixes were used. In fact, I would suggest the only reason persons understood what GB or TB meant (approximately) was the prefixes' SI roots (however loose). In the same way, it is likely that larger sizes will be termed PB, EB, ZB, YB, and so on, despite no computing body having suggested these or approved them as meaning multiples of 1024. It is not safe to assume that the prefixes (that bear an uncanny resemblance to SI prefixes) mean multiples of 1024 (or more correctly, multiples of 2^(10*n)) in the absence of any standard. As I surely have said previously: I have seen lots of different notations used for 1024 bytes, including: - k - K - kBytes - KBytes - Ko - ko - KB - kB - kb - KiB - kiB - KKB To call any of the above uniform practise would be untrue. Indeed, "KB" is probably now the most widely used, but it is not by any means uniform, unambiguous, or standardized, not to mention that the 1000 v. 1024 issue is not addressed. It surprises me that when a well-respected engineering body *does* propose a standard, that most persons I have talked to are in fact against it! > > SI TI (french for "IT", I'm guessing) I guess it would be "technologie informatique" or something similar, but I see no need for this standard to have a French name! :-) > k = 1000^1 K = 1024^1 > M = 1000^2 M = 1024^2 > G = 1000^3 G = 1024^3 > etc... >>I am not aware of *any* standard that prescribes >>1 kilobyte = 1024 bytes, as it is clearly incorrect. >> > > Other than the de facto standard, of course. Sorry; it's the standards > that are incorrect if they presume to tell us that 1 kilobyte does not > equal 1024 bytes. Now I've seen official standards (aerodynamic > reference frame stuff) that required me to call "up" "down", and one > must go along with such things sometimes. Interesting. In common usage (as enforced by SI), kilo does indeed mean 1000. A related analogy is that the IEEE proposal is merely ensuring that "up" always means "up", instead of possibly meaning "sort of up but a little bit sideways" in computing. >>The *only* official statement on this matter I am aware of is the one >>the IEEE, IEC, and CIPM were involved in which clearly states: >> >>1000 bytes = 1 kilobyte (symbol "kB") >>1024 bytes = 1 kibibyte (symbol "KiB") >> >>By continuing the current practise (which I must say is far from >>uniform), we are continuing inaccuracy and ambiguity. >> > > But using "kB" to mean 1000 bytes would be worse than ambiguous; I expect that most of the current references to "KB" or "kB" actually (erroneously) refer to a kibibyte (1024 bytes), so there would be few instances where you would see "kB" for 1000 bytes until the standard became well-known. > it would mislead most of the many FDP readers who don't take the time to > memorize the FDP introductory material on documentation standards. I don't wish to blame, but perhaps it is the readers' mistake in assuming that kilobyte meant 1024 bytes in the first place (again, this is not a standard or even uniform in use). > I'd call such use inaccurate in an FDP context. Again, "kB" and "MB" would seldom be seen in this document, as I expect in most cases 1024 is intended. The existence of references to KiB and MiB would surely alert the reader that there was some terminology they were not yet familiar with. Indeed, if you wanted to try to ensure that no ambiguity existed, the references to "kB", "KB", "KiB", or whatever could be hyperlinks to the place in the introduction, appendix, definitions, or the standard itself where this terminology is defined. Do not presume that every reader currently reads KB as 1024 bytes. Thanks for the interesting debate! :-) -- MICHAEL WARDLE | WORK +61-2-6024-2699 SGI Desktop & Admin Software | MOBILE +61-415-439-838 Adacel Technologies Limited | WEB http://www.adacel.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-doc" in the body of the messagehelp
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