R.S. wrote:
Bruce Hewson wrote:
Well folks,
until M$ came along, and before KiB became a standard, I was taught
the convention as:
Disk: always use decimal value, i.e. KB = 1000 Bytes.
Memory: always use binary value, i.e. KB = 1024 Bytes.
That made it easy:.....
It's not easy. For example, you cannot dump 15MB region of memory (RAM)
to 15MB file. It doesn't mention tapes, wires (10MB/s - is it "binary"
or "decimal" ?), etc.
BTW: I was taught different convention: IT uses k as 1024 (1kB = 1024
bytes), rest of the universe use k as 1000. That looks much easier for
me. Of course the best is unambiguous convention, like Ki,Mi,Gi etc.
Unfortunately it came very late, too late. People were using k,M,G as
"binary" prefixes for years, it's very hard to change their accustoms.
See non-metric measures in U.S. (*)
IMHO, that HDD vendors found a way to "increase" their capacities by
using "decimal" prefixes. They even tried to use "unformatted capacity",
but quickly gave up since, noone could use such capacity. Sometimes we
see "2.0MB" on 3.5" diskettes, those which we use as 1.44MB. I know,
there are ways to use non-standard format and have more than 1.44MB, but
it was never 2.0MB (usually 1.68-1.72 MB).
Caution: disktettes marked 'ED', sometimes used by IBM, at capacity
2.88MB is different story.
Now with M$ (and others), you never know where they use 1000 or use
1024 in their arithmetic to calculate the number they report to you on
memory or disk usage. Very much like the Mix-N-Match shops.
[snip]
It's not MicroSoft. It's the International Electrotechnical Commission.
They are a standards body. Here is a link to an article based on the
standard: http://www.iec.ch/zone/si/si_bytes.htm
To get the document itself you need to subscribe and pay. Or at
least pay.
Kind regards,
-Steve Comstock
The Trainer's Friend, Inc.
303-393-8716
http://www.trainersfriend.com
z/OS Application development made easier
* Our classes include
+ How things work
+ Programming examples with realistic applications
+ Starter / skeleton code
+ Complete working programs
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