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Re: [midatlanticretro] MFM Hard Drive Repair - Update!

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  • Dave McGuire
    ... You can always come here to get some.. -Dave -- Dave McGuire, AK4HZ New Kensington, PA
    Message 1 of 11 , May 1, 2012
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      On 05/02/2012 01:05 AM, Kyle Owen wrote:
      > Thanks Dave! And your large list of freebies really makes me regret not
      > being able to make it to VCF...those Sun servers sound awesome!

      You can always come here to get some..

      -Dave

      --
      Dave McGuire, AK4HZ
      New Kensington, PA
    • s100doctor
      ... This is awesome work, speaking as a digital engineer,. and a good description. I hope you took more than a few photos. I encourage you to put this work and
      Message 2 of 11 , May 2, 2012
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        Kyle Owen <kylevowen@...> wrote:
        >
        > I spent the last day or so taking apart and putting back together my 40 MB
        > hard drive from my PC/AT.

        This is awesome work, speaking as a digital engineer,. and a good description. I hope you took more than a few photos. I encourage you to put this work and description on a Web site; I'd be glad to make a Web page of it on my site, with other vintage repair and restoration work. Let me know accordingly.

        Herb Johnson
        retrotechnology.com
      • Kyle Owen
        Hi Herb, Thanks! To be honest, I had no clue I d have even remotely close to this much success. That being said, I did not think to photographically document
        Message 3 of 11 , May 2, 2012
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          Hi Herb,

          Thanks! To be honest, I had no clue I'd have even remotely close to this much success. That being said, I did not think to photographically document my progress. Darn! I figured I'd take the drive apart, screw something up more, put it back together to make it look nice, and maybe hang onto it for parts. But to have a working drive...I still can't get over that!

          I might take you up on the website offer still, if it's okay. I intend to do quite some stuff with my SWTPC 6800 this summer. One of my next projects for sure is making an 8k ROM board to take the place of the (4) 2k ROMs on the main board, as well as a loading utility to go with it (think about not having to wait five minutes to load BASIC!). The pins will be spaced such that no modification of the actual board will be required; just plug it in and go. With some modification to the board, you could instead have RAM installed at $C000, but I'm a purist: no traces shall be cut on my boards! 

          I've not made any significant progress on the 32k RAM board yet. Exams are all this week, so I've been trying to keep distractions to a minimum. However, I expect I will have the RAM card finalized by the end of the month. I am also working on designing a sound card, one using a 4-channel 8-bit DAC, and another using the popular AY-3-8910. The former will be able to fit on an SS-30 card, whereas the latter will likely be built into my RAM card, assuming I can fit it. I've not played much with the AY-3-8910, but it looks entertaining. As for the DAC sound card, I have to figure out a good way of mixing the channels appropriately. I was thinking pots, but it would be a nuisance to have to reach into the case to adjust the levels manually. Any thoughts?

          Is an 8k ROM card or a sound card (FM or sampled) something anyone would be interested in for the SS-50/30 systems? The ROM card would likely be SWTPC-only, as I am not sure if any others used the same spacing, or even a similar configuration of ROM.

          Kyle

          On Wed, May 2, 2012 at 11:31 AM, s100doctor <hjohnson@...> wrote:
           

          Kyle Owen <kylevowen@...> wrote:
          >
          > I spent the last day or so taking apart and putting back together my 40 MB
          > hard drive from my PC/AT.

          This is awesome work, speaking as a digital engineer,. and a good description. I hope you took more than a few photos. I encourage you to put this work and description on a Web site; I'd be glad to make a Web page of it on my site, with other vintage repair and restoration work. Let me know accordingly.

          Herb Johnson
          retrotechnology.com


        • joshbensadon
          Wow, nice job! Thanks for the great narrative on the repair! Wish there were some pictures to go with it. But I still felt like I was right there with you
          Message 4 of 11 , May 2, 2012
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            Wow, nice job! Thanks for the great narrative on the repair! Wish there were some pictures to go with it. But I still felt like I was right there with you rolling that bearing with a little pressure.

            Cheers!
            Josh
          • Dave McGuire
            ... Sorry for jumping in...how about digipots? There are ones with tap-up/tap-down control interfaces that d likely be easy to drive with just a decoded I/O
            Message 5 of 11 , May 2, 2012
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              On 05/02/2012 08:55 PM, Kyle Owen wrote:
              > As for the DAC sound card, I
              > have to figure out a good way of mixing the channels appropriately. I
              > was thinking pots, but it would be a nuisance to have to reach into the
              > case to adjust the levels manually. Any thoughts?

              Sorry for jumping in...how about digipots? There are ones with
              tap-up/tap-down control interfaces that'd likely be easy to drive with
              just a decoded I/O chip select line.

              -Dave

              --
              Dave McGuire, AK4HZ
              New Kensington, PA
            • Kyle Owen
              No worries...I wouldn t be posting to the group if I didn t want people jumping in! :) The only issue I see with using digital pots with my current design is
              Message 6 of 11 , May 2, 2012
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                No worries...I wouldn't be posting to the group if I didn't want people jumping in! :)

                The only issue I see with using digital pots with my current design is that the chip I'm using is has (4) channels, and each SS-30 card is only given 2-bits worth of address space. If I want to address all four channels individually, that won't leave me with any room for controlling the digital pots. Alternatively, I could have three audio wires coming off directly, and make an optional mixer board with a few op-amps. That would also reduce costs if you already have another mixer, or are only needing a channel or two, etc.

                I've been looking over the AY-3-8910 a bit, and it sounds like it could actually fit on the SS-30, with some extra decoding most likely.

                Any ideas as to what else would work nicely on a 32k RAM board? Currently, it's very bare, with only (4) ICs. And it's a big board for just a few ICs: 5.5"x9". 

                Kyle

                On Wed, May 2, 2012 at 11:27 PM, Dave McGuire <Mcguire@...> wrote:
                On 05/02/2012 08:55 PM, Kyle Owen wrote:
                > As for the DAC sound card, I
                > have to figure out a good way of mixing the channels appropriately. I
                > was thinking pots, but it would be a nuisance to have to reach into the
                > case to adjust the levels manually. Any thoughts?

                 Sorry for jumping in...how about digipots?  There are ones with
                tap-up/tap-down control interfaces that'd likely be easy to drive with
                just a decoded I/O chip select line.

                        -Dave

                --
                Dave McGuire, AK4HZ
                New Kensington, PA


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              • David Gesswein
                ... The standard way around that is you make one of the address an on board address register which then selects which device on the board another address
                Message 7 of 11 , May 3, 2012
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                  On Wed, May 02, 2012 at 11:57:42PM -0500, Kyle Owen wrote:
                  >
                  > The only issue I see with using digital pots with my current design is that
                  > the chip I'm using is has (4) channels, and each SS-30 card is only given
                  > 2-bits worth of address space. If I want to address all four channels
                  > individually, that won't leave me with any room for controlling the digital
                  > pots.
                  >
                  The standard way around that is you make one of the address an on board
                  address register which then selects which device on the board another
                  address accesses. Does slow things down since extra writes are needed
                  when you wish to talk to a different device. If one of the devices doesn't
                  use all the data bits you can take the extra bit for a pot/other chip
                  select.
                • s100doctor
                  ... I ll contact you offline from the MARCH list. I had forgotten we had been in email contact about your SWTPC 32K RAM design. I ll be curious to know how
                  Message 8 of 11 , May 3, 2012
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                    Kyle Owen <kylevowen@...> wrote:
                    >
                    > Hi Herb,
                    >
                    > Thanks! To be honest, I had no clue I'd have even remotely close to this
                    > much success. That being said, I did not think to photographically document
                    > my progress. Darn! I figured I'd take the drive apart, screw something up
                    > more, put it back together to make it look nice, and maybe hang onto it for
                    > parts. But to have a working drive...I still can't get over that!
                    >
                    > I might take you up on the website offer still, if it's okay.
                    > >

                    I'll contact you offline from the MARCH list. I had forgotten we had been in email contact about your SWTPC 32K RAM design. I'll be curious to know how many MARCH members have those systems - I know a few, Bill Degnan showed one last year at VCF.

                    Herb
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