"Bill in Co." <(E-Mail Removed)> wrote in message news:%(E-Mail Removed)...
> Bill Blanton wrote:
>> "Bill in Co." <(E-Mail Removed)> wrote in message
>> news:(E-Mail Removed)...
>>> When your right click on a drive in windows explorer, and get these
>>> different reported sizes, what is the story?
>>>
>>> Example, for a 20 GB partition - rounded to 3 significant digits below:
>>> (choose whichever I guess; the two listings below are seen next to each
>>> other in windows explorer):
>>>
>>> 12. 4GB 11.5 GB used spaee (tot capacity adds up to 19.9 GB)
>>> 7.56 GB 7.04 GB free space (tot capacity adds up to 18.6 GB)
>>> (tot = 19.9 GB) (tot = 18.5 GB)
>>>
>>> and as yet a third variation reported in BING:
>>>
>>> 11.9 GB used,
>>> 7.22 GB free
>>> (total = 19.1 GB)
>>>
>>> Anyone have a good explanation for the differences? I assume part of it
>>> might have to due with the defenition of the HD sizes, e.g.: 1 GB or 1.024
>>> GB, for "1 GB size" - not sure?
>>
>> Sorta,,, and your rounding of the bytes to GB shows why it's not the same
>> thing.
>>
>>> Take this last example;
>>>
>>>
>>> or for a 40 GB example:
>>>
>>> 20.36 GB 18.9 GB used space
>>
>> It wasn't 20.36GB was it? It was 20,36n,nnn,nnn bytes. So, divide that number
>> by 1024^3 (or 2^30) and you'd get roughly 18.9GB
>>
>>> 19.64 GB 18.2 GB free space
>>
>> Divide 19,64n,nnn,nnn by 1024^3, and you get roughly 18.2
>>
>>> capacity:
>>> 40.00 GB 37.2 GB
>>
>> So, bytewise
>>
>> + 20,36n,nnn,nnn
>> + 19,64n,nnn,nnn
>> = 40,nnn,nnn,nnn
>>
>> but 40,nnn,nnn,nnn bytes is not 40GB (in binary terms).
>
> Thanks Bill. I'll have to digest this a bit more. But there is still a point of confusion for me here. Giga just means 10 to
> the 9th, so I used that as shorthand, but maybe that is incorrect or misleading to do for binary expressions? Well, let's see...
>
> So if the disk capacity shows as 40,000,nnn,nnn bytes, it is not "correct" to express it as 40 X 10^9 bytes, or 40 E +09 bytes?
> (even though that is the actual "number"?)
10^9. That's not in-correct. That's how HD manufacturers define their drives.
And kilobits/sec, kilowatts, et al are de3fined by powers of 10.
However, Windows (more correctly IMO) defines storage space in powers of 2.
40GB = 40 * 2^30 = 42,949,672,960. (and since it isn't a power of 10 you
can't just move the decimal point to get to the next quantifier)
Since computers are mostly binary (n^2) beasts, (CPU, memory)
it was common in the early days to define a kilo-byte as 1024 bytes, and
not 1000 bytes (and so was "close enough"). I think it may have taken off
from there.
There was/is a movement under way to insert an "i' to denote binary ^2
to avoid the confusion. I.e KiB, Mib, GiB, TiB. It was supported by the IEC and
IEEE, but I don't think it ever really took off.
Here, I found this. (see "quantifiers")
http://www.ccil.org/jargon/jargon_32.html#TAG1443