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Thread: Temperamental A)IBM XT B)ST-225 C)Controller D)All of the above?

  1. #1
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    Default Temperamental A)IBM XT B)ST-225 C)Controller D)All of the above?

    Hello. My IBM XT has issues with its Seagate ST-225 hard drive. And it always had actually since I got it last year. I made a post around the time I got it here and in that post I mention the exact same hard drive problem. The problem is as follows. Sometimes, I will turn the computer on and the hard drive will work no problem. Other times, the hard drive will work at first but become unreadable after. Other times, the hard drive cannot be read from the moment it is powered on. Interestingly, when the hard drive is unreadable it is still detected by the computer, can still be accessed (but not read) and can still be parked. It sorts of act like as if it wasn't low-level formatted, I guess. Also interesting is that when it becomes unreadable its drive letter disappears from DOS. Typing C: does not say something like drive not ready, read error etc... It just says something like invalid drive letter even though previously in the same session it was there and readable! And when the drive is readable all the data is there and can be read flawlessly. So I don't know if it's a problem with the hard drive, the controller, or the computer itself... The controller is a DTC 5150BX I think.

    So that's the problem. Just looking at the controller itself makes me feel extremely anxious. There seems to be two ROMs but at least they are socketed. I don't know how to read them however. There are also 2 soldered PALs, and there seems to be many rare and proprietary parts on it.

    And interestingly, the hard drive seems to be connected backward to the controller. The pink stripes on the cables go from the first pins of the hard drive to the last ones of the controller... I didn't even know this was possible.
    • The only computer from my childhood that I'm missing is an Olivetti M380-40... Please help me find a solution to this problem
    • Looking for pictures of the following Olivetti computers: M380 W, M380 XP4, M400-60, M480... Complete list: http://pastebin.ca/3629976

  2. #2
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    Quote Originally Posted by 6885P5H View Post
    So I don't know if it's a problem with the hard drive, the controller, or the computer itself...
    You left out: bad connections, cables and power.

    For example. I have had intermittent hard drive problems caused by the connection from power supply to drive (plug into socket) not being as snug as it should.

    Dirty edge connectors.

    Many possibilities. I have spares of everything, and one advantage of that is so that in your kind of situation, I can norrow in on the cause of an intermittent problem relatively quickly.

    Quote Originally Posted by 6885P5H View Post
    The controller is a DTC 5150BX I think
    Both variations of DTC 5150BX that I have seen have "5150BX" printed on them.

    Quote Originally Posted by 6885P5H View Post
    And interestingly, the hard drive seems to be connected backward to the controller. The pink stripes on the cables go from the first pins of the hard drive to the last ones of the controller... I didn't even know this was possible.
    "First pins" and "last pins" do not always indicate the end where pin 1 is.

  3. #3
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    Currently the hard drive works. I re-partitioned it but it is unformattable. I can put some files on it but cannot sys it. I've never messed with an MFM hard drive before... When I attempt to format it it just gets lost for what seems like an eternity....
    • The only computer from my childhood that I'm missing is an Olivetti M380-40... Please help me find a solution to this problem
    • Looking for pictures of the following Olivetti computers: M380 W, M380 XP4, M400-60, M480... Complete list: http://pastebin.ca/3629976

  4. #4

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    Quote Originally Posted by 6885P5H View Post
    Currently the hard drive works. I re-partitioned it but it is unformattable. ....
    Kinda' a contradiction, doncha' think?
    PM me if you're looking for 3½" or 5¼" floppy disks. EMail “ ” For everything else, Take Another Step

  5. #5
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    Huhmmm, it works as in it doesn't act up in the way that I described above. If it didn't work, typing format c: would say something like drive not found.

    I don't know how these hard drives are supposed to work. Maybe I need to format it with a special utility I don't know ;(((( I'm afraid to mess something up, maybe I already did.
    • The only computer from my childhood that I'm missing is an Olivetti M380-40... Please help me find a solution to this problem
    • Looking for pictures of the following Olivetti computers: M380 W, M380 XP4, M400-60, M480... Complete list: http://pastebin.ca/3629976

  6. #6
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    Have you done a low level format on the drive? It has helped, or been absolutely necessary with nearly all the old MFM drives I have gotten. Many 8bit controllers have a low level format routine in the ROM, accessed from DOS by entering debug, and typing G=C800:5

  7. #7
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    No I haven't tried that. This is something that I have never done before and I'm afraid I could mess something up... I know that G=C800:5 (goto address C800, I don't know what the 5 means) is the generic method of performing a low-level format. I'd be interested in having a list of all the commands available for my controller. Maybe the generic command doesn't even work with it, I never tried it.



    **Off-topic** Apparently the 5 is an offset. I kinda forgot what an offset was but I think it means the fifth byte starting from C800. So G=C805 would work if the IBM XT had a 5-bit processor.... Hahaha probably not... I really don't remember how this stuff works.... I used to know what integers were. Words, longwords, shortwords... I forgot all of it.
    • The only computer from my childhood that I'm missing is an Olivetti M380-40... Please help me find a solution to this problem
    • Looking for pictures of the following Olivetti computers: M380 W, M380 XP4, M400-60, M480... Complete list: http://pastebin.ca/3629976

  8. #8
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    If doing a low-level format is required to format it in DOS, can I have some instructions? The controller asks me for an hard drive number. And after that an interleave factor.... And who knows what's next. Cylinders, heads, whatever else is written on TH99, I can write. The rest, I don't know what it is.
    • The only computer from my childhood that I'm missing is an Olivetti M380-40... Please help me find a solution to this problem
    • Looking for pictures of the following Olivetti computers: M380 W, M380 XP4, M400-60, M480... Complete list: http://pastebin.ca/3629976

  9. #9
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    I just wanted to agree with fatwizard said above. I do it on all my machines when they arrive because it's only a matter of time before it wont be able to find it's marbles anymore.

    Low Level Format, then partition in FDISK, then format with DOS.
    It'll be blank, but likely work like a charm for years to come afterwards.

    Edit: Drive number would be 0, interleave on a 4.77Mhz XT .... I think 5 would be ideal.

    Heads 4
    Tracks/Cylinders 615
    Sectors per track: 17
    Write Precomp: 300
    Reduced Write: 616

    Shouldn't need much else?
    Last edited by SpidersWeb; May 11th, 2017 at 03:55 PM.
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  10. #10
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    This hard drive used to work fine (when it didn't act up). I deleted its partition, created a new one. I then saw that it couldn't be formatted. And now it's stuck in a weird state where files can be put on it, but it cannot be sys'd and a few other oddities (like chkdsk saying that the disk is a probable non-dos disk). A low-level format could fix this? Maybe.

    Can you tell me what drive number and interleave are? Why do you say 0 and 5? The controller says that the default interleave is 6 by the way.

    What is reduced write, where did you get that info?
    • The only computer from my childhood that I'm missing is an Olivetti M380-40... Please help me find a solution to this problem
    • Looking for pictures of the following Olivetti computers: M380 W, M380 XP4, M400-60, M480... Complete list: http://pastebin.ca/3629976

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