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2nd try: Maxtor XT-2190 MFM Hard Drive Controller (apologies)

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  • chetwyndplace
    My apologies to everyone...my previous message on this topic contained a picture that was too big, and cut off most of this message (or sent you a lot of
    Message 1 of 5 , May 11 4:11 PM
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      My apologies to everyone...my previous message on this topic contained a picture that was too big, and cut off most of this message (or sent you a lot of garbage characters).  Here it is again without the picture:

       

      I am wondering if anyone here might know the "best" MFM Hard Drive Controller to use with a Maxtor XT-2190 MFM hard drive, in a Compaq Deskpro 386 PC?

       

      (the linked website is not my drive pictured, but mine are just like it...and these pics are great!)

       

      The MFM interface is something that was a few years before my time, so my recent discovery of it is a new thing for me.

       

      My ultimate goal is to read some data from one of these that was written in a UNIX branded OS called CTIX...

       

      However, I've set myself up with some technology that I know a little better in order to learn about it.  The 386 PC is something I remember well as a user, but never did much system configuration.  I thought I would approach my project in several stages.

       

      Stage 1)  Configure my Compaq 386 to format and access a spare XT-2190 using DOS.

       

      Stage 2)  Once that works, install and configure SCO Xenix on the same machine, and format another XT-2190, to play with it using that OS.

       

      Stage 3)  Plug in and browse the CTIX/Unix formatted drive with the data, and see what I can find.

       

      I have 4 of these Maxtor XT-2190s to play with, not including the one that has the data.

       

      So far, I've acquired 2 controllers, but not exactly sure where to start...I don't even know if they control the right number of heads & sectors for this size MFM drive, and, for those of you how have browsed my blog or other posts, I continue to have some issues getting an ISA card to work right in my machine...I'm almost afraid to play with these.

       

      1) Data Tech Corp DTC 5280CRA PC/AT HARD DISK & FLOPPY DISK CONTROLLER

      http://ebay.com/itm/111304188857


      bit.ly/1meIS55

       

      2) Xebec 8 Bit MFM Hard Drive Controller Card (104836-01)

      http://ebay.com/itm/191124319994


      http://museum.ttrk.ee/th99/c/U-Z/21079.htm 

       

      I'm loosely creating a blog for the machine that the drive came out of (in scatterbrain fashion...sorry...).  It's a Convergent Technologies MightyFrame. 

       

      http://MightyFrame.com

       

      I've decided that one way or another, I'm going to figure out these machines, and this seems to be an approach that might at least be a good step-learning process for me.

       

      I welcome anyone's thoughts.  Everyone here is very helpful.

       

      Thanks to everyone for their input!

       

      -AJ

       

       

       

       

       


    • David Gesswein
      ... Like was said there are an annoying number of low level formats for disk drives out there. If you can t find a controller that will read it I have been
      Message 2 of 5 , May 11 6:32 PM
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        On Sun, May 11, 2014 at 04:11:12PM -0700, chetwyndplace@... [midatlanticretro] wrote:
        > I am wondering if anyone here might know the "best" MFM Hard Drive
        > Controller to use with a Maxtor XT-2190 MFM hard drive
        >
        Like was said there are an annoying number of low level formats for disk
        drives out there. If you can't find a controller that will read it I have
        been working on a MFM reader/emulator. I'll be at the next MARCH work
        day.

        http://www.pdp8online.com/mfm/mfm.shtml

        I probably can get the physical sector contents with it. Converting to
        logical sectors if the controller does fancy stuff is left as an exercise
        to the user.

        I'll also let people get in on the PCB order when I order some for me.
      • David Comley
        ... Looks like a great project and is much needed work as so many people are struggling with MFM drives failing these days. Please bear me in mind when you do
        Message 3 of 5 , May 12 4:41 AM
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          ----- Original Message -----

          > From: "David Gesswein djg@... [midatlanticretro]" <midatlanticretro@yahoogroups.com>
          > To: "chetwyndplace@... [midatlanticretro]" <midatlanticretro@yahoogroups.com>
          > Cc:
          > Sent: Sunday, May 11, 2014 9:32 PM
          > Subject: Re: [midatlanticretro] 2nd try: Maxtor XT-2190 MFM Hard Drive Controller (apologies)

          > Like was said there are an annoying number of low level formats for disk
          > drives out there. If you can't find a controller that will read it I have
          > been working on a MFM reader/emulator. I'll be at the next MARCH work
          > day.
          >
          > http://www.pdp8online.com/mfm/mfm.shtml
          >

          Looks like a great project and is much needed work as so many people are struggling with MFM drives failing these days. Please bear me in mind when you do an order for PCBs as I'd love to build one.

          -David
        • jeff_s_jonas
          I m unsure what controller chip was the best, but I suspect it s a combination of controller chip, clock recovery circuit & device drivers. Ideally, disks spin
          Message 4 of 5 , May 12 7:39 AM
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            I'm unsure what controller chip was the best, but I suspect it's a combination of controller chip, clock recovery circuit & device drivers. Ideally, disks spin at constant speed. In reality, it wavers depending on things like bearing, if the motor's directly in the hub or to the side via a belt, etc. The signal processing for reading needs to tolerate that.

            Old controllers were 3:1 interleave. Then 2:1. You probably want a 1:1 since that'll read older ones. 16 bit interface, not 8. I think they were all PIO, not DMA.

          • Dave McGuire
            ... Those variations, within reason, are handled via PLL-based clock recovery circuitry in the controller. They tend to work pretty well. ... For a given
            Message 5 of 5 , May 12 12:52 PM
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              On 05/12/2014 10:39 AM, jeff_s_jonas@... [midatlanticretro] wrote:
              > I'm unsure what controller chip was the best, but I suspect it's a
              > combination of controller chip, clock recovery circuit & device drivers.
              > Ideally, disks spin at constant speed. In reality, it wavers depending
              > on things like bearing, if the motor's directly in the hub or to the
              > side via a belt, etc. The signal processing for reading needs to
              > tolerate that.

              Those variations, within reason, are handled via PLL-based clock
              recovery circuitry in the controller. They tend to work pretty well.

              > Old controllers were 3:1 interleave. Then 2:1. You probably want a 1:1
              > since that'll read older ones.

              For a given on-disk format, a slower (higher interleave factor)
              controller will still read a drive written with a lower interleave
              factor, it will just be dog slow because it'll usually just get one
              sector per revolution.

              -Dave

              --
              Dave McGuire, AK4HZ
              New Kensington, PA
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