Weekly Classic Computer Trivia Question (20141205)

Eric Smith spacewar at gmail.com
Fri Dec 5 21:55:05 CST 2014

On Fri, Dec 5, 2014 at 8:13 PM, Mouse <mouse at rodents-montreal.org> wrote:
>> It's not, it's 10**12.
> You don't get to tell us how we use language any more than anyone else
> does.

Nor any less.

NIST, IEC, and ISO will tell you that using SI prefixes for powers of
two is wrong.  I suspect that Standards Council of Canada will as
well, but I haven't looked into it.

On the other hand, disk drive vendors will tell you that they define
KB, MB, GB, and TB as 10^3, 10^6, 10^9, and 10^12 bytes, respectively.
If you buy their 1TB drive expecting to get 1024^4 bytes of storage,
you'll be disappointed, and you likely won't have any legal recourse
because the vendor puts that definition in all of their marketing
literature and on the product packaging.

So who is right, disk drive vendors or the standards bodies? It's a de
facto vs. de jure distinction.

> (For that matter, if you buy a
> "4G" stick of RAM, would you be perfectly happy to get one containing
> no more than 4,000,000,000 bytes?

I make a point of buying 4 GiB DIMMs rather than 4 GB.  The gibi
prefix (defined as 1024^3) is part of the International System of
Quantities (ISQ, ISO/IEC 80000-13:2008).  SI ("the metric system"),
which defines the decimal prefixes, is also part of ISQ.

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