b & B, k & K, m & M; was BSO on the radio - not for me anymore

Garrett Wollman wollman@bimajority.org
Fri Oct 15 22:12:34 EDT 2010

<<On Fri, 15 Oct 2010 21:24:11 -0400, "Dan.Strassberg" <dan.strassberg@att.net> said:

> The difference between MB and mb is not seven decimal orders of
> magnitude but 10. M = Mega = 10^6; m = milli = 10^-3. 6-(-3) = 9. Nine
> decimal orders of magnitude (that is, a factor of 1 billion) right
> there. B/b = 10^1, so there's one more. 9+1 = 10. 10^10 = 10 billion.

The nice folks at the International Electrotechnical Commission -- the
electrical and electronic counterpart to ISO -- have invented a new
system of prefixes for the "binary" system (based on powers of 2^10).
The reception has thus far been mixed; some organizations have gone
completely over to the new system of mebibytes and kibibytes and
gibibytes, but others have laughed and said, "That's ridiculous,
everyone knows that a megabyte is 1,048,576 bytes!"  There is a real
danger of confusion when people who deal with primary data storage --
measured in powers of 2^10 -- have to communicate with people who deal
with data communications -- measured in powers of 10^3.  And the
secondary-storage people (i.e., disk drive manufacturers) sell storage
in multiples of 512 bytes, but use the 10^3-based (standard SI)
prefixes since it makes their capacities sound bigger.  (For a modern
one-terabyte hard drive, the difference is about 9%.)

The IEC prefixes are "Ki", "Mi", "Gi", "Ti", and so on up to "Zi".


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