20" imac intel's hard disk capacity: 233 GB. not 250 GB claimed by Apple's specification

Discussion in 'Apple' started by dualline, Mar 18, 2006.

  1. dualline

    dualline Guest

    Bought a new imac intel 20". Found that the capacity of its built-in
    hard disk is not 250 GB but 233 GB. Why?
    dualline, Mar 18, 2006
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  2. dualline

    Tom Stiller Guest

    This question has been asked and answered at least a dozen times. You
    really should check the archives before asking obvious questions.

    The difference arises because drive manufacturers use the (correct)
    decimal value of 10^9 to represent "giga", while most computer software
    uses 2^30 to represent "giga".

    The arithmetic is left to the reader.
    Tom Stiller, Mar 18, 2006
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  3. dualline

    Edward Doty Guest

    The difference is probably because of the difference in how
    manufacturers count. Most companies claim that 250 GB is
    250,000,000,000 bytes, while computers count in increments of 1024.
    Read the fine print in the specifications and you'll see that they
    consider 1 GB to be 1,000,000,000 bytes instead of 1,073,741,824 bytes.
    Edward Doty, Mar 18, 2006
  4. dualline

    Mathue Guest

    Not to sound snippish or anything, but..

    Why does this question keep having to be answered, YEAR AFTER YEAR?

    I recall this coming up over what a 3.5 floppy holds! :)


    From article:

    Consumer confusion

    Note that computer memory is addressed in base 2, due to its design, so
    memory size is always a power of two. It is thus convenient to measure
    in binary units. Other computer measurements, like storage hardware
    size, data transfer rates, clock speeds, operations per second, and so
    on do not have an inherent base, and are measured in the usual decimal
    units. Consumers who are (initially) unaware of varying meanings of the
    abbreviations often feel shortchanged when they discover the
    difference, and claim that manufacturers of drives and data transfer
    devices are using the decimal measurements in an intentionally
    misleading way to inflate their numbers, though these measurements are
    the norm in all fields other than computer memory and storage.
    For instance, if a hard drive is said by a vendor to store 140 GB of
    data, the disk can store 140?109 bytes. Generally, operating systems
    allocate and report disk and files sizes in binary units, and present
    them using abbreviations (e.g GB, MB, KB) also used by the decimal
    system, so this drive would be reported as "130 GB" (actually 130.36
    GiB). Some have even sued these manufacturers for deceptive
    advertising, because of the discrepancy. (Another complication is that
    the drive wouldn't be able to store files with a total filesize of
    130.36 GiB, either, due to filesystem overhead. See Partition
    Mathue, Mar 18, 2006
  5. dualline

    Steve Hix Guest

    Because disk drive formatting overhead uses up part of the total disk
    capacity. The drive does have that much space, it's just that some of it
    is taken up by necessary data beyond your own stuff.
    Steve Hix, Mar 18, 2006
  6. No, that's not the reason for this discrepancy. The overhead will not
    take up a whopping 17 GB!! The reason is explained in the other answers:
    binary versus decimal numbers.
    Johan W. Elzenga, Mar 18, 2006
  7. dualline

    Al Guest

    In my opinion, the confusion stems from advertisers mixing apples and
    oranges. In days of yore, a kilobyte was defined as 1028 bits, and so
    on. I don't think there was anyone working in the profession who was
    confused by it.

    Now we have the great unwashed trying to deal with the concept. Most can
    only count to ten because they have ten fingers. They never did
    understand the concept that number systems can have diffenent bases and
    that they are consistent within themselves.

    Now that some European standards group has declared that kilo means
    1000, the great unwashed think they can apply the prefix kilo to byte
    and think it means 1000 bytes. In reality, a kilobyte was, and always
    will be 1028 bytes.

    Al, Mar 19, 2006
  8. dualline

    Tom Stiller Guest

    I will agree that advertisers make claims that tend to make their
    products seem more attractive, but that example doesn't show then mixing

    As far back as I can remember, and probably before computers existed,
    the prefix kilo has meant one thousand, as in kilogram, kilometer, etc.

    The confusion is sort of akin to measuring television screen sizes on
    the diagonal. Not too many people remember that CRTs used to be round
    and the diameter was the only measurement that indicated sizes. When
    rectangular tubes were produced, the diagonal measurement was introduced
    to provide a level of comparison between the old and the new. Round
    CRTs have pretty much gone the way of the Dodo, but the diagonal
    measurement persists.
    As long as all drive manufactures use the same terminology, meaningful
    comparisons can be drawn and, except for idle curiosity, the difference
    between 1000 and 1024 doesn't matter.

    Context is everything. Would you sell 1024 grams of gold for the price
    of a kilogram?
    Tom Stiller, Mar 19, 2006
  9. Try "1024 bytes". 1028 bits is 0.125 kilobytes with 50 cents left over.
    To be fair, the standards group declared that long before their use in
    computers. More recently, they've come up with the abominations
    "kibi", "mibi", and "gibi", abbreviated "Ki", "Mi", and "Gi", and they
    want the rest of us to use them. Now that's gross; I refuse to use
    such gibirish.
    Matthew Russotto, Mar 19, 2006
  10. dualline

    Al Guest

    Ahh, somebody is listening. I bite (pun intended) my tongue.

    Al, Mar 19, 2006
  11. dualline

    J Stewart Guest

    Last time I looked that was 1024 (2 to the 10 power) not 1028.
    J Stewart, Mar 19, 2006
  12. The European standards group which declared this was active during the
    French Revolution. If you can give an earlier citation for the use of
    "kilo" to mean 1024, I'd be interested to see it.
    William Mitchell, Mar 20, 2006
  13. It's this what's called the "marketing overhead"
    Michael Vilain, Mar 20, 2006
  14. dualline

    dualline Guest

    Actually I had searched it via goole group before I posted it. I now
    realize that the question has been asked quite often here with your
    information. A FAQ.

    In othe words, it IS really a problem to customers in computer
    industry, as the others indicated here.

    Thank you all for your reply.
    dualline, Mar 20, 2006
  15. dualline

    Per Rønne Guest

    Because most harddisk manufacturers cheat on the bathroom scales ...

    In computer science, 233 G = 233 * 2^30 bytes. But the harddisk
    companies say it only means 233 * 10^9 bytes. 250*10^9/2^30 = 232.831

    In physics, 1 G = 10^9. In the computer industry 2^30.
    Per Rønne, Mar 20, 2006
  16. dualline

    Per Rønne Guest

    Consequently, we always used to discriminate between K [meaning 2^10]
    and k{ilo} [meaning 1000].
    Per Rønne, Mar 20, 2006
  17. dualline

    Steve Hix Guest

    D'oh... I knew that. Brain fault.

    (But still, formatting data *does* take up some disk space. Almost
    nothing compared to the binary/decimal innumeracy. But still....
    Only so far as marketing takes advantage of the combined
    laziness/stupidity of using the same prefixes to describe different
    things. "Kilo" *should* refer to 1000, and *shouldn't* be used to
    describe 1024.

    We're almost too late to disambiguate the issue; it's not clear yet
    whether or not the "Gibi" (Giba?) construction will actually see
    widespread popular acceptance/understanding.
    Steve Hix, Mar 20, 2006
  18. dualline

    Steve Hix Guest

    So we try to plug the hole in the dike with GiB...
    Steve Hix, Mar 20, 2006
  19. dualline

    Per Rønne Guest

    That's the reason for choosing K and k as examples - I perfectly knows
    what you wrote.
    Per Rønne, Mar 21, 2006
  20. dualline

    Jd Lyall Guest

    I think that "European standards group" made that decision a few
    thousand years ago. Kilo, does in fact mean one thousand. Probably long
    before western (or any?) mathematicians comprehended the utility of base
    2 mathematics. Base 60 was used WAAY long ago tho.
    Jd Lyall, Mar 27, 2006
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