Puzzle: Reading 1988 Mac Floppies

Discussion in 'General Mac Discussion' started by Chris70, Jan 10, 2004.

  1. Chris70 macrumors newbie

    Jan 10, 2004
    Here's a question for a historical
    I have some floppies made on a
    Mac in January 1990. A modern G5
    will not read them. A M$ Windoze XP
    machine, after installing MacDrive5,
    also can't recognized the format.

    What are the most modern machines
    that should be able to read them??
    (Modern enough to find on campus
    I hope).

    The machine that wrote them was
    color, and likely one of these
    models (so 800kb or 1.4mb I don't know):

    Macintosh IIci 1989 Floppy Drive: 1.4 MB SuperDrive
    Macintosh IIx 1988 Floppy Drive: 1.4 MB SuperDrive
    Macintosh II 1987 Floppy Drive: 1 or 2 800k 3.25" (upgradable to 1.4 MB SuperDrive)
    Macintosh Plus 1986 Floppy Drive: 3.5" 800 kb

    My thanks to the long term Mac expert
    who can answer this!
    Added later:
    The floppies say on them:
    "MD2DD Double Sided,
    Double Density, Double Track"
  2. MoparShaha macrumors 68000


    May 15, 2003
    San Francisco
    Does the floppy have the "HD" logo on it? If so, it's high-density (1.4 MB). If it's a low-density 800K disk, you might be out of luck. I know the old SuperDrives could read both, but it wouldn't surprise me if newer floppy drives only read high-density. Another possibility is that the disks are corrupt. Floppy disks randomly became corrupt frequently, so do not discount that possibility. If you're still stuck, and desperately need the data on the disks, you could just buy an old Mac on eBay for $20-$30 that would read them.
  3. simX macrumors 6502a


    May 28, 2002
    Bay Area, CA
    If you know someone who has an Imation SuperDisk Drive, those can read both 800K and 1.4 MB floppy disks. However, they cannot read 400K floppy disks (which is REALLY annoying). So you'll need to find an old Mac if you have a 400K disk to read.

    There's a simple way to identify a 400K disk. If you look at an 800K or 1.4 MB disk, you'll notice that they will have a hole in both the upper left and upper right corners. One is for the disk lock thingy, and the other is to signify it's a higher capacity disk. 400K disks only have 1 hole, for the disk lock thingy -- I don't remember if it's on the left or right, but I think it's on the top right. In any case, it doesn't really matter.

    (Funny anecdote: you can actually convert a 400K disk to an 800K disk SIMPLY BY PUNCHING A HOLE IN THE DISK. It sounds counterintuitive that you just have to make a physical hole in the floppy disk, but it works. I believe the reason is that 400K disks are only single-sided, but technology later came that allowed computers to write on both sides, and it didn't require any change in the media. So computers identify the capacity of the disk by this hole.)
  4. Chris70 thread starter macrumors newbie

    Jan 10, 2004
    I am the original question poster.
    The floppies say on them:
    "MD2DD Double Sided,
    Double Density, Double Track"
    Thank you. -Chris
  5. MoparShaha macrumors 68000


    May 15, 2003
    San Francisco
    Hmm. That's probably not a good sign then. You have high-density 1.4 MB disks, so they should be readable by any floppy drive. I think the disks are probably corrupt.
  6. Chris70 thread starter macrumors newbie

    Jan 10, 2004
    Is DD the same as HD ??

    From original poster asking question:
    Thank you simX and MoparShaha.
    But are you sure "DD" equals "HD"?
    "DD" = 720 kb or 800 kb (double density?) and
    "SD" = 360 kb or 400 kb (single density?) and
    "HD" = 1.44 MB (high density?). Maybe.
    I found some retail new blanks like this:
    Mfg. Part #90099; 3.5 in; Capacity 1 MB
    (Top of above page say HD and 1.44;
    while last product on page says
    DD and 720kb.)

    What do you think? Are these 1.44MB or 800KB ?
    And if they are 800kb, what was the last
    (newest) Mac model that could read these?
    -Chris :confused:
  7. GraphicUmp macrumors member

    Sep 29, 2002
    Mid Atlantic
    Double-density are 800k disks. Can be read by G3 Beige and earlier.

    High-density are 1.4 MB disks.
  8. MisterMe macrumors G4


    Jul 17, 2002
    Not every drive can read 1.44 MB disks. The first Apple floppy disk drives capable of reading HD disks was the original SuperDrive. SuperDrives were introduced in 1988 on the Mac IIx. High density floppies are distiinguished from double density floppies by a permanent hole in the case directly opposite the write-protect hole. There was another difference that many people are not aware of. True HD floppies used a magnetic recording medium that was incompatible with the DD medium. However, most floppy disk manufacturers used the same medium for both. Most floppy drives could not detect the difference in media.
  9. MoparShaha macrumors 68000


    May 15, 2003
    San Francisco
    Ah yes, totally forgot about that. Sorry for the mistake.
  10. cubist macrumors 68020

    Jul 4, 2002
    Muncie, Indiana
    My USB floppy drive won't read 800K disks, only 1.44MB disks.

    The 1.44MB disks use MFM like other floppy disks, but the 800K (DSDD) uses a GCR (group-coded recording) specific to Apple. You will have to find an older Mac with a built-in floppy drive to read them.

    Another point is that the magnetic fields are very small. Floppy disks are only rated for data retention for 15 years. Beyond that point, the probability is greater than 50% that data errors will render the data unreadable. Your disks are 14 years old - you are on the hairy edge of losing your data.

    One of the selling points of ablative WORM was that the disk's data retention was over 50 years. I don't think CD-R has as long a life. Does anyone quote data retention of DVD-Rs?

    (edit) If it was the Macintosh Plus, the machine may have had single-sided (400K) drives. Such disks are only readable in very old Macs. I have a Mac Plus. Where are you located?

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