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Re: [midatlanticretro] How do I make boot floopy? IMSAI + Northstar + CP/M?

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  • telmnstr
    ... Is it possible to just format any SS/DD or DS/DD 5.25 into hard sectored? Or are the floppies made different somehow at the factory? ... My IMSAI has some
    Message 1 of 19 , Mar 27, 2013
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      > I can make copies of the master disk for you, but you'll still have to
      > patch the I/O for your system. The other thing is, these are hard-sector
      > disks. I don't have a ton of them on hand at the moment, as I haven't
      > gotten around to placing an order with Athana. When do you need disks
      > by?

      Is it possible to just format any SS/DD or DS/DD 5.25" into hard sectored?
      Or are the floppies made different somehow at the factory?

      > I can also probably patch the I/O for you, if your I/O can be
      > duplicated/emulated by a board I currently have. What are you planning
      > on using for the system console?

      My IMSAI has some sort of serial card that doesn't look very production.
      It's brown with two molex connectors at the top. The traces are kind of
      curvey, and not raw copper but tinned copper or something. It looks like
      a really good job of something someone made at home? It has one eprom on
      it that has CC-8 written on it.
    • Systems Glitch
      ... They have extra holes punched at the same distance from the edge of the cookie as the index hole. For instance, the 10-sector variety (there are others,
      Message 2 of 19 , Mar 27, 2013
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        > Is it possible to just format any SS/DD or DS/DD 5.25" into hard sectored?
        > Or are the floppies made different somehow at the factory?

        They have extra holes punched at the same distance from the edge of the cookie as the index hole. For instance, the 10-sector variety (there are others, too) used by North Star have 11 holes at the same radial distance as the usual single index hole.

        It's possible to punch the holes with a jig, but I don't have one. I've also heard the acceptance rate is somewhat low with hand-punched disks as the punch tends to make a bump in the disk cookie.

        > My IMSAI has some sort of serial card that doesn't look very production.
        > It's brown with two molex connectors at the top. The traces are kind of
        > curvey, and not raw copper but tinned copper or something. It looks like
        > a really good job of something someone made at home? It has one eprom on
        > it that has CC-8 written on it.

        Can you attach/link a picture? If it's something homebrew, or even if it's production but the manual can't be found, it'll have to be reverse engineered to figure out where it falls in I/O or memory address space. I'd first determine if it uses I/O space or if it's memory mapped, then see if you can easily figure out the decode circuit. If not, put a logic probe on one of the chip select pins or bus driver enables, and start probing address space.

        Thanks,
        Jonathan
      • joshbensadon
        ... So is mine, they are very good capacitors. I brought them up slowly then did a ripple test on them. Power supply = 8.2V while drawing 5Amps with 620mV
        Message 3 of 19 , Mar 27, 2013
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          --- In midatlanticretro@yahoogroups.com, Systems Glitch <systems.glitch@...> wrote:
          >My IMSAI is running on the capacitors that came with it, as is the Cromemco Z-2D and CompuPro 8/16. That doesn't mean yours are guaranteed good, of course. Do bring it up on a variac to help in the reforming process if you want to try and keep the old caps.
          >
          > Thanks,
          > Jonathan


          So is mine, they are very good capacitors. I brought them up slowly then did a ripple test on them.
          Power supply = 8.2V while drawing 5Amps with 620mV ripple.

          Looked good enough for me. Last I checked, the drop out voltage of those 5V regulators was 7V.

          :)J
        • Systems Glitch
          ... Yup, that s sufficient! They ll regulate down to 7V; in fact, that s what I run my DC bench supply at when I use it with a small S-100 backplane. The 78/79
          Message 4 of 19 , Mar 27, 2013
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            > Looked good enough for me. Last I checked, the drop out voltage of those 5V regulators was 7V.

            Yup, that's sufficient! They'll regulate down to 7V; in fact, that's what I run my DC bench supply at when I use it with a small S-100 backplane. The 78/79 series regulators have pretty good ripple rejection if you provide adequate bypass around them.

            Thanks,
            Jonathan
          • s100doctor
            ... http://www.classiccmp.org/dunfield/img/index.htm I dont have time tonight to check Dunfield s disk images, to see if he has single-density N* disk images.
            Message 5 of 19 , Apr 1 4:13 PM
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              > telmnstr@... wrote:
              > > I just looked. MDC-A4 is the floppy controller.
              >
              > Ah well... I owe Jonathan a beer. As he pointed out, this
              > is not good news. The CP/M stuff on Dave Dunfield's site
              > is double density. You should probably follow his lead
              > from here on out. I've never played with the one single
              > density N* controller I have and I've never played with N*
              > DOS.

              >
              > Bill S.
              >
              http://www.classiccmp.org/dunfield/img/index.htm

              I dont' have time tonight to check Dunfield's disk images, to see if he has single-density N* disk images. Check for yourself, later. But his Northstar NST serial transfer tools may be of some use to you. Since Dave's disk imaging can't make hard-sectored diskettes, he uses the native system to create or read the disk image and transfers it by serial cable to the MS-DOS system where the image files are created/read.

              People re-invent this technology over and over again; Dave's had a set of these transfer tools for various systems, for some time.

              herb
              retrotechnology.com
            • Systems Glitch
              ... Yes, he does...no CP/M but plenty of North Star DOS and related applications/usergroup disks. ... It definitely works with single-density disks, that s how
              Message 6 of 19 , Apr 2 8:37 AM
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                > I dont' have time tonight to check Dunfield's disk images, to see if he has single-density N* disk images.

                Yes, he does...no CP/M but plenty of North Star DOS and related applications/usergroup disks.

                > But his Northstar NST serial transfer tools may be of some use to you.

                It definitely works with single-density disks, that's how I made mine. I don't recall right off whether I had to do anything special for single-density.

                > People re-invent this technology over and over again; Dave's had a set of these transfer tools for various systems, for some time.

                Sticking with a known-good imaging system and image format also helps to grow the available software for the community.

                Thanks,
                Jonathan
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