360k or 720k ? - CP/M

This is a discussion on 360k or 720k ? - CP/M ; I'm trying to ID all my floppy drives to find the rare, elusive 720k 5.25" drives. Google finds nothing for this one: half height CDC Control Data Company MOD 9429 01 PN 77743004 LOT # 8429 SN s-112614 thanks in ...

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Thread: 360k or 720k ?

  1. 360k or 720k ?

    I'm trying to ID all my floppy drives
    to find the rare, elusive 720k 5.25" drives.
    Google finds nothing for this one:
    half height
    CDC Control Data Company
    MOD 9429 01
    PN 77743004
    LOT # 8429
    SN s-112614

    thanks in advance!

    -- Jeffrey Jonas
    jeffj@panix(dot)com
    The original Dr. JCL and Mr .hide
    --

    -- mejeep deMeep ferret!

  2. Re: 360k or 720k ?

    Jeff Jonas wrote:
    > I'm trying to ID all my floppy drives
    > to find the rare, elusive 720k 5.25" drives.
    > Google finds nothing for this one:
    > half height
    > CDC Control Data Company
    > MOD 9429 01
    > PN 77743004
    > LOT # 8429
    > SN s-112614
    >
    > thanks in advance!
    >
    > -- Jeffrey Jonas
    > jeffj@panix(dot)com
    > The original Dr. JCL and Mr .hide

    I have a pair, but see, technically, they aren't 720k 5.25, although
    they do seek that far. They are actually 77 tracks, and the head step is
    different enough that 1.2MB drives can't read them. :-)

    These were made by Magnetic Peripherals, Inc... AKA Control Data.

    Part # I got is 77711503, and it's full hight. My guess is that you got
    a 77 track, not an 80 track drive.

  3. Re: 360k or 720k ?

    Jeff Jonas wrote:

    > I'm trying to ID all my floppy drives
    > to find the rare, elusive 720k 5.25" drives.


    If you just want a drive to use, an PC style HD drive
    with the right signal on pin 2 will do it.
    That is, assuming you have non-HD media.

    If you have HD media with the appropriate signal on
    pin 2, it should be able to write at 720k instead
    of the normal 1.2M, though maybe slightly less
    reliably. The precompensation might be different, too.

    I think it is pin 2 ground for HD media, and floating (high)
    for non-HD, but I might have forgotten that one.

    -- glen


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