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Thread: Hard Sector Floppy: Revisited

  1. #11
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    Yes--the way a hard-sector floppy works is that additional holes are punched at the same radius where one would normally expect only a single index hole. Said index hole now is positioned midway between two sector holes. Simple enough to pick out the index with a couple of one-shots.


  2. #12
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    Thank you Chuck....

    For the factory made Hard-sector floppies, were the holes only
    in the magnetic media or they were punched through the jacket
    as well?

    ziloo

  3. #13
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    Nope--just the cookie. It wouldn't make sense to punch the jacket.

  4. #14
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    Oh I see now....
    All holes will go through the jacket's index hole and will be
    detected right there. The size of the index hole and sector holes
    must be the same then.

    ziloo

  5. #15
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    Yes--only the spacing differs. The index occurs between two sector holes.

  6. #16

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    For more information, The H89 didn't require the logical sectors to match the physical sectors. I would
    format floppies that skipped to sector holes for each logical sector for a friend that had a lot of "read" data
    in BASIC programs. It made a lot of programs a lot faster to load. So another myth down. The media was exactly
    the same. I even have some polymorphic 5.25 disk recorded in double density.
    My Nicolet does require specific locations for sector relative to the index hole. It uses 32 hard sectored disk but
    only has 2 sectors covering 1/2 the disk each. It does single density with 2 sectors of 2.5K bytes each. This compares
    with normal single density of 4K for a hole side or less.
    Hard sectored used a simple, off the shelf, USART and simple clock data separator.
    What made soft sectored popular was the WD, simple, single chip solution. This both of these made the system ROMless disk controller
    less practical for things like S100's. People were willing to give up having systems with a real, full, 64K of RAM for the cheaper
    controller and a system boot ROM, eating some of the address space. ( there were workarounds but they were rarely used )
    As Chuck mentioned, even though, hard sectored disk most all used the same FM or MFM data but things like sector/track addresses
    were not any standard. WD made this a standard that only had slight differences. This is why you can copy many classic computer
    disk on a PC ( may require single density that many PC controllers didn't support ).
    Dwight

  7. #17
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    Thank you Dwight!

    Then, hard-sector floppy didn't require low level formatting that
    is needed for soft-sector floppies....is that right?

    ziloo

  8. #18

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    Quote Originally Posted by ziloo View Post
    Thank you Dwight!

    Then, hard-sector floppy didn't require low level formatting that
    is needed for soft-sector floppies....is that right?

    ziloo
    In all cases I saw, they required some form of formatting. In the case of the Nicolet, it needed some way to determine
    that it had reached the correct track other than recalibrate from track0. It had no sync as it always had a field of clocks
    before the track number of 7 bits.
    Technically, it could live without such formatting. The H89 had sync, track and sector headers at each sector.
    So in general I'd say one still needs some form of header.
    Dwight

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