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Thread: WTB: MFM controller for 5150

  1. #11

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    I think there is a Utah vintage group on Facebook.

    There is always a chance the drive is no good also. Did it get parked before the controller was removed? I have a 5170 that had a bad RAM chip in bank 1 when I bought it. It got shipped all over the country and I’m pretty sure that’s why the ST-225 is very questionable now, since it wouldn’t post it couldn’t be parked before moving it.

  2. #12
    Join Date
    May 2006
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    Quote Originally Posted by JNZ View Post
    The HDD is a WD25 IBM HDD, with apparently no information on the drive about its geometry.
    Cylinders = 306 / Heads = 8 / SPT = 17 / WPC = 128

    Quote Originally Posted by JNZ View Post
    I believe this is the original type of drive that comes with the computer, ...
    According to my notes, it was one of the 20MB drives that IBM optionally supplied in the later model 5160's (together with the third variation of controller shown at [here]).

    Quote Originally Posted by JNZ View Post
    ... and might be considered "type 13" for the BIOS.
    Well, for the BIOS on an AT motherboard.

  3. #13

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    There is another way to recover contents of drives without the original controller. http://www.pdp8online.com/mfm/. Probably overkill for just reading one drive.

    The head positioning is handled by the drive so that doesn't effect the controller. Its mostly changes to the sector header format and CRC/ECC codes.
    From what I have seen for formats most of it looks to be the standard we want to do our own thing. Some was driven by desire to add additional capability such as jumperless configuration, handling of bad sectors by the controller, and ECC codes to allow recovery from some read errors. Adaptec went their own way with LBA addressing. Others by not planning ahead. Format in the ST-506 manual only allocated one byte for cylinder which wasn't enough for their next drive the ST-412. The non PC controllers are much worse than PC controllers for weird formats.

  4. #14

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    Thanks for all the information. I'm going to try a Xebec rev. 3 to start with. I'm almost tempted to find someone who has a card that can back it up like that, as this is an old work computer...But given the age of the computer it's unlikely to have any fun older versions of code.

  5. #15

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    Keep in mind that it's not uncommon for MFM drives to fail from age alone, even while sitting on the shelf for years. I've had lots of them go south that way. Track zero problems are not unusual either and that's a nonstarter.
    PM me if you're looking for 3" or 5" floppy disks. EMail For everything else, Take Another Step

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