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Date:      Thu, 14 Jun 2012 08:40:27 +0100
From:      Matthew Seaman <m.seaman@infracaninophile.co.uk>
To:        freebsd-questions@freebsd.org
Subject:   Re: `ls -l` shows size of file other than of the folder?
Message-ID:  <4FD9956B.2010501@infracaninophile.co.uk>
In-Reply-To: <20120614081107.c0439718.freebsd@edvax.de>
References:  <CAD2Ti2-%2BD1og9TS8E-vJO2fPg77SRGW%2BXq6bFq0kpOnR=fs0aw@mail.gmail.com> <20120614081107.c0439718.freebsd@edvax.de>

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On 14/06/2012 07:11, Polytropon wrote:
> In IT context, already in the 60's and 70's, unit prefixes
> k, M and G always were interpreted as of 2^n (or 1024*),
> even if the unit was _words_, not bytes. :-)

Which was incorrect in principle

> Even school taught that in the 80's: When dealing with
> computers, 1 kB !=3D 1000 B, but 1 kB =3D 1024 B. That is
> considered basic knowledge.

Schools teach a lot of things that are so glossed over or so
over-simplified as to be basically wrong.  They have been known to teach
things that were common knowledge at the time and were later shown to be
simply incorrect[*].

> Every IT person should be aware of this. It's common to "abuse"
> the SI units with the (known!) deviant interpretation.

Really?  If I said the bandwidth usage was 10Mb/s would you immediately
understand that was 10,000,000,000 bits per second?  Yes, bandwidth is
always denoted in strict SI powers-of-1000 scale modifiers, always has
been, but the corrosive effect of muddling 2^10 vs 10^3 in computing
just leads to confusion and error.

> Sometimes, you find hardware vendors "forgetting" the factor
> mismatch 1024 vs. 1000 when they tell you how many GB the new
> shiny hard disk has. :-)

Oh dear.  It is so galling to realise that the sales people were
actually right all along isn't it?  Does one's geek credibility no good
at all to realise that we've been out pedanted by some suits...

SI has published the standard for byte-wise scale factors: Ki, Mi, Gi
etc.  Best to start using them immediately and pretend that the whole
shameful episode of being unable to distinguish 1024 from 1000 never
ever happened.

	Cheers,

	Matthew

[*] I have memories of school lessons stating definitively that there
were only 2 allotropes of carbon[+]. Buckminsterfullerene wasn't
discovered until I was at University.

[+] Although this was factually incorrect at the time of teaching: look
up lonsdaleite.  Just because it never occurs in any more than
microscopic amounts doesn't mean it doesn't matter.


--=20
Dr Matthew J Seaman MA, D.Phil.                   7 Priory Courtyard
                                                  Flat 3
PGP: http://www.infracaninophile.co.uk/pgpkey     Ramsgate
JID: matthew@infracaninophile.co.uk               Kent, CT11 9PW




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