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sd card gets an I/O error

Discussion in 'Hardware' started by roshamboe, Aug 7, 2009.

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  1. roshamboe

    roshamboe Thread Starter

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    im not sure if i posted this in the right place, please forgive me if i didnt but i recently bought a PNY 4gb Micro sd card. when i put inside my computer, and go to my computer and click to open drive F, i get a message that says,
    "F:\ is not accessible"
    "The request could not be performed because of an I/O device error"
    i dont have a seperate adapter to use my card, there is already one built into my desktop computer but i openint it on my cousins computer and it worked fine.
     
  2. ruggb

    ruggb

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    4GB is an SDHC card. your card slot sounds like it is not HC compatible.

    Warning: some card readers advertised as being HC compatible are not.
    that is from experience.
     
  3. roshamboe

    roshamboe Thread Starter

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    thanks for the reply, but i tried my friends 2gb sd card and it worked fine, what makes them different besides the size? and is there any way i can make my card slot HC compatible?
     
  4. ruggb

    ruggb

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    A 2 GB card is NOT HC
    A 4GB card IS HC.

    HC incompatibility appears to be the issue.
    I need to research that, there must be another address line to access the higher memory.

    I don't think u can make non-HC compatible into compatible.
    Unless the mfg has a software fix.
    adapter cards do not.
    I am not sure what the actual difference is but it is probably the address line.
    adapter readers are cheap, BUT not all readers advertised as HC compatible actually are.

    If u buy one and it doesn't work with 4GB but does with 2GB (as it does now) the reader has the same issue.
     
  5. ruggb

    ruggb

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    this is some of what makes them different. It is a software function to be able to read different sizes.

    most readers appear to have the firmware burned into them and can't be changed.

    ========================================



    Devices that use SD cards identify the card by requesting a 128-bit identification string from the card. For standard-capacity SD cards, 12 of the bits are used to identify the number of memory clusters (ranging from 1 to 4096) and 3 of the bits are used to identify the number of blocks per cluster (which decode to 4, 8, 16, 32, 64, 128, 256 or 512 blocks per cluster).
    In older 1.x implementations the standard capacity block was exactly 512 bytes. This gives 4096 x 512 x 512 = 1 gigabyte of storage memory. A later revision of the 1.x standard allowed a 4-bit field to indicate 1024 or 2048 bytes per block instead, yielding more than 1 gigabyte of memory storage. Devices designed before this change may incorrectly identify such cards, usually by misidentifying a card with lower capacity than is the case by assuming 512 bytes per block rather than 1024 or 2048.
    For the new SDHC high capacity card (2.0) implementation, 22 bits of the identification string are used to indicate the memory size in increments of 512 KBytes. Currently 16 of the 22 bits are allowed to be used, giving a maximum size of 32 GB. All SDHC 4-GB and larger cards must be 2.0 implementations. Two bits that were previously reserved and fixed at 0 are now used for identifying the type of card, 0=standard, 1=HC, 2=reserved, 3=reserved. Non-HC devices are not programmed to read this code and therefore cannot correctly read the identification of the card.
    All SDHC readers work with standard SD cards.
     
  6. roshamboe

    roshamboe Thread Starter

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    ok ill just get a seperate card reader off ebay for 2 bucks, thanks
     
  7. ruggb

    ruggb

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    buyer beware.

    the box may be labeled HC compatible, but that is not a guarantee that it is.
    I bought 3 from dealextreme and the blue one was not.
    the black "All-In-One" with a cable and a memory stick style one are fine, though the cable was bad on the AIO.

    A micro card reader for Ebay for 25 cents worked fine also.
     
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