strange problem trying to compare files. - Microsoft Windows

This is a discussion on strange problem trying to compare files. - Microsoft Windows ; I have a floppy disk that I have discovered has unreadable sectors, some experimentations with this disk has shown some strange things I hope someone can explain. The drive doesn't seem to be able to tell that it is writing ...

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  1. strange problem trying to compare files.

    I have a floppy disk that I have discovered has unreadable sectors, some
    experimentations with this disk has shown some strange things I hope
    someone can explain.

    The drive doesn't seem to be able to tell that it is writing to the bad
    sectors so, when I copy a file to the disk, no errors result. I want to
    confirm that the data on the disk is good, so I try to compare the file on
    the disk with the original. When I try this, though, the compare succeeds,
    but, produces no floppy disk access. If I go do something else for a while
    and come back to it and compare again, now I get floppy disk access and the
    compare fails with an os message "cannot read from the specified device".
    any subsequent compare I try fails, only a compare that occurs immediately
    after writing the file to the disk passes with no disk access.

    If I restart in msdos mode and try this, the first compare I try produces
    disk access and the compare fails.

    Why, in windows (win98), doesn't the first compare produce disk access? and
    why do I get good data out of a file that is unreadable?

  2. Re: strange problem trying to compare files.


    "hashi" wrote in message
    news:Xns9623D2A674440776852d3f2@news.aioe.org...
    > I have a floppy disk that I have discovered has unreadable sectors, some
    > experimentations with this disk has shown some strange things I hope
    > someone can explain.
    >
    > The drive doesn't seem to be able to tell that it is writing to the bad
    > sectors so, when I copy a file to the disk, no errors result. I want to
    > confirm that the data on the disk is good, so I try to compare the file on
    > the disk with the original. When I try this, though, the compare succeeds,
    > but, produces no floppy disk access. If I go do something else for a while
    > and come back to it and compare again, now I get floppy disk access and

    the
    > compare fails with an os message "cannot read from the specified device".
    > any subsequent compare I try fails, only a compare that occurs immediately
    > after writing the file to the disk passes with no disk access.
    >
    > If I restart in msdos mode and try this, the first compare I try produces
    > disk access and the compare fails.
    >
    > Why, in windows (win98), doesn't the first compare produce disk access?

    and
    > why do I get good data out of a file that is unreadable?


    It's likely that win98 is retaining the data in a buffer in memory. When
    doing the compare, the OS sees no reason to read the physical device since
    the data it thinks it wrote to the disk is still in memory. It therefore
    compares the buffer in memory to the data it was trying to write to the
    device IMHO.



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