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

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  • Bill Sudbrink
    ... IMSAI SIO might be a good assumption, might not. Just in terms of what I ve seen, there are a lot of odd ball serial cards out there. ... Oh! Don t get
    Message 1 of 19 , Mar 26, 2013
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      Systems Glitch wrote:
      > You'd be surprised. I got Bill Degnan's Vector Graphic ZCB strapped up
      > to operate with its console port at the standard North Star addresses.
      > If it's Intel 8251/8251A based (as the IMSAI SIO was) there's a good
      > chance it can be made to look like the North Star serial console port.
      > Anything with a 40-pin 1402 descendant UART can be made to look close
      > enough if it supports strapping the status bits individually.

      IMSAI SIO might be a good assumption, might not. Just in terms of
      what I've seen, there are a lot of "odd ball" serial cards out there.

      > > Or you could patch the diskette image before you transfer it from the
      > > PC to the IMSAI.
      >
      > Yes, this is true. I like working with old stuff, though!

      Oh! Don't get me wrong, I like toggling the front panel as much as the
      next guy. It's just that when I'm trying to get an OS up, I like a
      little more repeatability.

      > Huh, I must be the odd case then...I've got three working single-
      > density controllers, all acquired with other piles of S-100 boards. I'd
      > just assumed they were equally common.

      Maybe it's a region thing. Most of mine came from Craig's list ads and
      hamfests in the Washington DC region.

      > > I think I have the tools to generate a single density CP/M boot disk.
      > > Remind me when the next VCF gets closer and I'll try to make you one.
      >
      > Awesome, thanks! I was thinking about getting CP/M 3 working with it,
      > since it handles sector sizes other than 128 bytes natively.

      Be sure to remind me or I will forget.

      Bill S.
    • telmnstr
      I just looked. MDC-A4 is the floppy controller. Looks like a video card, and there is a serial card but I haven t identified it. The cards are in there... very
      Message 2 of 19 , Mar 26, 2013
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        I just looked. MDC-A4 is the floppy controller.

        Looks like a video card, and there is a serial card but I haven't
        identified it. The cards are in there... very tough to pull out.

        4 ram cards as well.

        I'm going to look to replace the 4 huge electrolytic caps on the psu.




        On Tue, 26 Mar 2013, Bill Sudbrink wrote:

        > Systems Glitch wrote:
        >> Depending on the card you're using, you can set it up to appear
        >> enough like the North Star serial interface to get things up and
        >> going.
        >
        > That's a pretty major "depending". There seem to have been dozens
        > of different serial cards, each using different I/O addresses,
        > different bits in the byte to indicate status. That's why Processor
        > Tech went to such lengths on the 3P+S. You could strap everything
        > on that card.
        >
        >> Or you can patch the I/O routines into the OS once it loads from disk
        >
        > Or you could patch the diskette image before you transfer it from the
        > PC to the IMSAI.
        >
        >> You may also run into an issue with which North Star controller you
        >> have -- there are two, a single-density version (old, original one) and
        >> the double-density version (used in the Horizon).
        >
        > I'll bet you a beer at the next VCF East that, if he has a N* controller,
        > it's an mds-ad3. I have one single density controller -vs- a whole
        > stack of ad3s. Totally by accident, found at random as I've added to
        > my collection.
        >
        >> There are more pre-built OS disks available for the double-density
        >> version. I've yet to find a prebuilt CP/M image for the single-density
        >> controller (does anyone know of one? I'm almost certain they had to
        >> have existed at one point).
        >
        > I think I have the tools to generate a single density CP/M boot disk.
        > Remind me when the next VCF gets closer and I'll try to make you one.
        >
        > Bill S.
        >
        >
        >
        >
        > ------------------------------------
        >
        > Yahoo! Groups Links
        >
        >
        >
        >
      • Bill Sudbrink
        ... 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
        Message 3 of 19 , Mar 26, 2013
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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.

          > I'm going to look to replace the 4 huge electrolytic caps
          > on the psu.

          That might not be necessary. If you look in the message
          archive, there was recently a discussion about bringing up
          old linear power supplies. I have a number of operating
          S-100 systems, including two IMSAI chassis, and I've never
          had to replace one of the big caps.

          Bill S.
        • telmnstr
          ... Uhhh okay. If I asked on the Vintage computer forum, I suppose I might be able to find someone willing to sell a copy of the boot floppy? That would get me
          Message 4 of 19 , Mar 26, 2013
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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.

            Uhhh okay.

            If I asked on the Vintage computer forum, I suppose I might be able to
            find someone willing to sell a copy of the boot floppy? That would get me
            the ability to boot the thing and make backup copies, then redirect serial
            to file.

            > That might not be necessary. If you look inthe message > archive,
            there was recently a discussion about bringing up
            > old linear power supplies. I have a number of operating
            > S-100 systems, including two IMSAI chassis, and I've never
            > had to replace one of the big caps.

            Ah okay. I know in the arcade world the large "big blue" atari caps and
            such get replaced, but those arcade machines generally have years and
            years of uptime while I'd imagine some of the classic computers do not.
          • joshbensadon
            Hi, I recently got my IMSAI 8080 to boot up CP/M on 8 . It wasn t easy. First things first. Make sure you have a good working system, especially check the RAM
            Message 5 of 19 , Mar 26, 2013
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              Hi,

              I recently got my IMSAI 8080 to boot up CP/M on 8".
              It wasn't easy. First things first. Make sure you have a good working system, especially check the RAM for errors.

              The 5-1/4" drives should be writable by a PC, check Dave Dunfield's website for compatibility for Single Density disks. He's got a utility that tests your controller chip on the PC.

              Rich Cini has also been doing a lot of great work in creating CP/M disks. Check out his site, just google his name + "Classic Computing"

              I took the ground up approach to getting CP/M running by writing my own format and disk read/write routines, then I transferred CP/M via XMODEM to the IMSAI. I had a lot of hardware to fix along the way.

              Cheers,
              Josh




              --- In midatlanticretro@yahoogroups.com, telmnstr@... wrote:
              >
              > I own an IMSAI 8080 in beautiful condition.
              >
              > It has an external Northstar badged floppy that matches the machine.
              >
              > I'm looking for pointers on making a bootable CP/M disk for it?
              >
              > Can I write it with a 5.25" tied to a standard PC or does it require a
              > Catweasel type board / existing old computer?
              >
              > There is a small local one day gaming event coming up in my area at the
              > Chesapeake Virginia library. They're showing Wargames at night so I'm
              > thinking maybe I should bring the IMSAI out.
              >
            • Systems Glitch
              ... Not the best news for CP/M, but not bad news in general! The single-density controllers seem to be very robust. ... Negative. No one there seems to have a
              Message 6 of 19 , Mar 27, 2013
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                > As he pointed out, this is not good news.

                Not the best news for CP/M, but not bad news in general! The single-density controllers seem to be very robust.

                > If I asked on the Vintage computer forum, I suppose I might be able to
                > find someone willing to sell a copy of the boot floppy? That would get me
                > the ability to boot the thing and make backup copies, then redirect serial
                > to file.

                Negative. No one there seems to have a working single-density controller and/or single-density disks. I still haven't figured out for sure if the double-density controller can read/write single-density. Bill Degnan made a copy of what he'd been told was a single-density master disk, but either it was mis-labeled or the double-density controller always writes in double-density as it didn't work for me. That's why I ended up creating my own disks from images using Dave Dunfield's NST.

                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?

                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?

                > Ah okay. I know in the arcade world the large "big blue" atari caps and
                > such get replaced, but those arcade machines generally have years and
                > years of uptime while I'd imagine some of the classic computers do not.

                It just depends on the caps. Some are of better quality than others, and age has a lot to do with it too. 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
              • 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 7 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 8 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 9 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 10 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 11 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 12 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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