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  1. #1
    Registered User thaxman's Avatar
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    SD card failures?

    Hi, just seeking some slightly off-subject info. I bought 2 cheap 128K SD cards less than a year ago, and suddenly they both failed. One can't be recognized by the 7135 or the SD reader, the other forces freezes when data is accessed. How bulletproof is an SD card really supposed to be?

  2. #2
    Cornfused MGuzzy's Avatar
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    They can loose thier format... try reformating them in your 7135 and see if that brings them back to life. If you haven't found it, there is an option to format the card in the Card Info app.
    mg
    Luck is where opportunity meets preparation.

  3. #3
    Registered User thaxman's Avatar
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    the one that causes the freezes is fine now, I deleted some MP3s it wouldn't read. How do I fix the one that the 7135 can't recognize? Is there a way to make it read it? I am a little confused.

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    Try to reformat the SD card outside of the 7135, using a USB card reader or another PDA, but your card may be damaged.

    My first SD card, a Lexar 256, was apparently defective and frequently would erase itself or freeze up and I couldn't reformat it in my 7135, though other devices could get a handle on it and reformat.

    I returned it and exchanged it for a PQI 256 which has never given me any trouble at all ever.

  5. #5
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    Um, I wrote that first sentance badly. It should have read something to the effect of "but your SD card may already have been damaged". Formatting the SD card in another device will not damage the card.

  6. #6
    Registered User thaxman's Avatar
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    Does anyone know why my 128 card went down to 121 after formatting it? I lost at least 6Mb.

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    A formatted storage device (SD card, harfdfile, etc.) always has less formatted space available than the spec size. The control info put on the device when it is formatted uses space too. The spec size (e.g., 128 MB, 1 GB, etc.) is the raw storage space available before formatting.

    Just as a matter of interest, K, M, G, etc., when used in connection with memory, are not metric multipliers. They are binary multipliers where, for example, K is a multiplier of 1024 (2 to the 10th power). So a 128 MB memory device actually has 134,217,728 bytes of addressable storage space. Also, B is bytes, b is bits. There are 8 bits (b) in a byte (B). SD sizes are typically specified in megabytes (1 MB = 1,048,576 bytes) or gigabytes (1 GB = 1,073,741,824 bytes).
    Last edited by tedcmiller; 10-19-2005 at 08:49 AM.

  8. #8
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    Originally posted by tedcmiller
    Just as a matter of interest, K, M, G, etc., when used in connection with memory, are not metric multipliers. They are binary multipliers where, for example, K is a multiplier of 1024 (2 to the 10th power). So a 128 MB memory device actually has 134,217,728 bytes of addressable storage space. Also, B is bytes, b is bits. There are 8 bits (b) in a byte (B). SD sizes are typically specified in megabytes (1 MB = 1,048,576 bytes) or gigabytes (1 GB = 1,073,741,824 bytes).
    For memory CHIPS, but not memory CARDS like SD, CF, MS, etc. These folks are cut from the same cloth as folks that market hard drives - they are using powers of 10, NOT powers of 2, in their specs.

    In the past, proper use of the letter kay was UPPER case for 1024 and lower case for 1000. But that technique falls apart for larger values since metric uses both upper and lower case em. For just this reason, IEC some years ago devised the concept of Ki, Mi and Gi for power of 2 nomenclatures, as compared to k, M, & G for powers of 10.

    It IS an international standard. The IEEE, international society for electrical and electronic engineers, supports it too.
    For more info, reference NIST's description

    Question is how long will it take for folks to start using it?
    Old habits die very hard and very slooowly. How many decades ago was it now that the US gov't tried to start gradually converting over to the metric system?
    Last edited by ReadOnly; 10-19-2005 at 08:51 PM.

  9. #9
    Registered User thaxman's Avatar
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    Unfortunately, I am not as well versed on storage space as I would like to be, but I do know that after my 1st format, I had 126-127 of available space, then after my reformat (in the 7135), it went down to approx 121, and that an alien folder appeared that cannot be opened, read or deleted.

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    ReadOnly, I looked at the NIST web site you pointed to and have the following comments:

    The problem of unit designations that can be based on powers of 10 or powers of 2 has been around a long time. When memory sizes were small, using K to indicate a multiple of 1024 (rather than k for a multiple of 1000) worked nicely. When memory sizes increased, M was used both for multiples of 1,048,572 and 1,000,000 because m was already used in the metric system to indicate a multiplier of 1/1000 (milli, as in millimeter or mm). It matters not whether you are talking about chips, cards, or hardfiles, they all use binary addressing. If hardfile manufacturers are advertising capacity in mulitples of 1,000,000 rather than multiples of 1,048,572, it is obviously for the purpose of making their devices look bigger. In my opinion, the IEC scheme makes a somewhat diffcult situation worse. It should be noted that, to the best of my knowledge, data rates (e.g., 10 Mbps Ethernet) have never used binary multipliers. That is, 10 Mbps means 10,000,000 bps and always has.

  11. #11
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    In my opinion, the IEC scheme makes a somewhat diffcult situation worse.
    Hardly.
    You must not have understood the new standard.
    It has the backing of two of the most recognized electrical and electronics standards organizations in the world. It was developed specifically to avoid confusion for both the lay person and specialists outside of a specific field.
    Neither organization is prone to making up new units and standards just for the heck of it.

    As for other electrical concepts using kay, em, and gee like communications standards:
    If one understands computer technology at the bit level, it would be obvious which items engineers deviated on from standard metric prefix usage.

    For those that don't, either ask for clarification (hopefully using the newer, more precise Ki/Mi/Gi standards), or be ready to be corrected.

    As for hard drive marketing folks - OF COURSE they went for the metric "M" specmanship advantage in a consumer commodity market. That's being redundant with stating their from marketing!

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    ReadOnly, I understand what is on that web site perfectly. Understanding something and approving of it are two completely separate issues. I personally see no need for any new or additional prefixes or multipliers. You yourself said that adoption of these new standards will probably take a very long time or might never happen at all. You cited the US Government's attempt to move everything to the metric system as an example. I understand the current standards and am quite happy with them. You should feel free to embrace the new stuff if you so desire. Anyone who wants to correct me can certainly do so. So far, you are the only one.

  13. #13
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    Originally posted by tedcmiller
    ReadOnly, I understand what is on that web site perfectly. Understanding something and approving of it are two completely separate issues. I personally see no need for any new or additional prefixes or multipliers.
    ...
    You yourself said that adoption of these new standards will probably take a very long time
    ...
    I understand the current standards and am quite happy with them. You should feel free to embrace the new stuff if you so desire. Anyone who wants to correct me can certainly do so. So far, you are the only one.
    Oh. I see.
    It is not that you don't understand the need, nor the solution -
    it's just that you don't "want to".
    That's ok. That's exactly why I said it would take a while to catch on. It has already been several years now, and progress has been slow.
    In the meantime, as I said before, just be prepared to be corrected for incorrect usage of the old nomenclature. Like what happened above when you posted an incorrect correction of someone else's usage, and again when you mused over whether ethernet speeds were affected by this impromptu standard's failure.

    Cheers. And good luck!

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