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    SubjectRE: reading from devices in RAW mode
    Date
    > > Is it such a newby question? Your suggestion of using dd is totally NOT
    > > what I meant: I want to read from devices with the devices ignoring
    their
    > > CRC-checks and such. Like what the CDROMREADRAW ioctl does for CD-ROMs.
    > CD-ROMs, floppy disks, and hard disks work in completely different
    > ways:
    > All modern forms of storage use powerful error correction below the
    > sector level. Floppies are the exception here, they typically use MFM
    > encoding, which is relatively straightforward.
    > Audio Compact discs use powerful error correction anyway, but CD-ROMs
    > use some of the capacity which was previously used for audio data for
    > a second level of error correction, so there are two sector sizes,
    > (RAW, and COOKED). Reading RAW sectors, does not come close to
    > allowing you to read individual pits and flats on the disc, it just
    > lets you bypass the top level of error correction. The data is still
    > being error corrected by lower layers.

    oh, ok. But I will still get more data back then with reading through
    the regular, say, /dev/hdc-device wouldn't I? As far as I know, read
    will only give you data when no I/O error occured.

    > There is no floppy or hard disk equivillent to reading raw sectors
    > from CD-ROMs.

    Really? Are you really sure about that?

    Back in the old days, when I did assembly on my Atari ST, I would just
    say to the controller "gimme this and that track, in RAW" and it
    would do so. I thought that I could do that at least for floppy, not
    sure about harddisk (RLL through ACSI interface).

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