Question for flash memory gurus.

Discussion in 'Digital Photography' started by Tony Karp, Jun 2, 2006.

  1. Tony Karp

    Tony Karp Guest

    I have a Panasonic FZ5 and 2 2GB SD cards for it.

    One card is a pq1 2GB, the other is Sandisk Ultra II 2GB.

    The actual amount of memory on the two cards is different. The Sandisk causes
    the camera to report 804 shots available, and the pq1 says 703.

    I checked the actual amount of memory on each card by putting it into a card
    reader and then checking its properties under Windows XP.

    Sure enough, there is a difference. The Sandisk card checks out with about 30
    megabytes more than the pq1.

    Actual values:

    Sandisk: 2,032,271,360 bytes
    pq1: 2,001,928,192 bytes

    The only thing I can think of is that while the cards are in QA, defective
    blocks are mapped out, and if it's within a certain percentage, it can still be
    specified as that size.

    Any other guesses?
     
    Tony Karp, Jun 2, 2006
    #1
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  2. Tony Karp

    Dave Guest

    Dave, Jun 2, 2006
    #2
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  3. Tony Karp

    Dave Cohen Guest

    Check if fat or fat32 under properties and if different how they got
    that way.
    Dave Cohen
     
    Dave Cohen, Jun 2, 2006
    #3
  4. Tony Karp

    Dave Cohen Guest

     
    Dave Cohen, Jun 2, 2006
    #4
  5. Tony Karp

    Tony Karp Guest

    I don't think that the cited lawsuit is the same as my issue. All drives (disk
    or flash) have less capacity than stated.

    The issue here is that two drives of the same size have slightly different
    capacities.
     
    Tony Karp, Jun 2, 2006
    #5
  6. Tony Karp

    Tony Karp Guest

    Under XP's Properites window, they both just say "FAT".

    But whatever the formatting is, they both have the same formatting since I
    reformatted them both in the camera.
     
    Tony Karp, Jun 2, 2006
    #6
  7. : The issue here is that two drives of the same size have slightly
    : different capacities.

    There are several reasons for this. First as has been pointed out, durring
    the manufacturing process there will be some of the memory elements that
    will test as bad and be locked out. Also there is some internal software
    that may differ from manufacturer to manufacturer that can take up a small
    part of the listed memory, and thus make it unavailable for your use. But
    there is also another problem. A "Gig" means different things to different
    people. In strict computer terms it is a multiple of a binary number.
    While the mathematical terminology is a multiple of a decimal number.
    For example 1K in math terms is 1000, while in computer terms 1K is 1024
    (and if you get silly 1K in physics terms is a temperature). :) So as the
    numbers get larger the difference in terms also grows. 1 gig is generally
    something between 1 billion (math) and 1,073,741,824 (binary). And due to
    the confusion between various terminology, manufacturers are able to get
    away with setting their own standards somewhere between the two.

    So just accept that if your card is somewhere in the range between 2
    billion and 2,147,483,648 you have a 2 gig card.

    Randy

    ==========
    Randy Berbaum
    Champaign, IL
     
    Randy Berbaum, Jun 3, 2006
    #7
  8. Tony Karp

    RW+/- Guest

    Might they be using different figures for what constitutes a megabyte?

    Similar to what Maxtor and Western Digital differences.
     
    RW+/-, Jun 3, 2006
    #8
  9. Tony Karp

    Steve Wolfe Guest

    I don't think that the cited lawsuit is the same as my issue. All drives
    See my other post in regards to the definition of a megabyte.

    As 1,000,000,000 bytes is not just the standard designation in the storage
    industry, it's also the semi-official standard definition of a gigabyte, so
    both of the card sizes which you referenced give you at least 2 gigabytes.
    Not necessarily the gigabytes you're thinking of, but still gigabytes.

    steve
     
    Steve Wolfe, Jun 3, 2006
    #9
  10. Tony Karp

    Steve Wolfe Guest

    Yes, they do... but that's not the issue.

    The real issue is "What, exactly, is a megabyte?"

    For quite some time, a megabyte was assumed to be 2^20 bytes, or 1,048,576
    bytes. However, that doesn't really fit the definition of the SI prefix
    "mega", which means 1,000,000. Because of that, hard drive manufacturers
    took the liberty of using the term "megabyte" to mean 1,000,000, while most
    of your software assumes it to be 1,048,576.

    If you define a megabyte as 1 million bytes, then a 256-megabyte card has
    256,000,000 bytes. If you define it as 2^20, then it has 268,435,456.
    Because Sandisk calls it a million and your computer doesn't, then a 256 meg
    card looks like 256,000,000/1,048,576, or... 244 megabytes.

    What's odd to me is that Sandisk could lose this case. First, the use of
    1,000,000 bytes as a megabyte has been the standard in the hard drive
    industry for quite a number of years. It's common practice. Second, some
    time ago, the IEC took it upon themselves to make recommendations as to the
    standard definiteion of megabyte, and they recommended... 1,000,000 bytes.
    Either way, I don't see how Sandisk could truly be guilty of overstating the
    capacity.

    The largest problem with the IEC's recommendation is that using terms like
    "mebibyte" and "gibibyte" is just about enough to make all of your friends
    stop associating with you in public.

    steve
     
    Steve Wolfe, Jun 3, 2006
    #10
  11. Tony Karp

    Kevin Agard Guest

    They count funny. And I'm not being a smartass here. Different
    manufacturers define a megabyte (or gigabyte) diferently.
     
    Kevin Agard, Jun 3, 2006
    #11
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