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Possibility of an Altair floppy disk emulator?

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  • tkaragiris
    Things have been a bit quiet in this group lately, so let me throw this one out there. I take an interest in several other vintage machines aside from the
    Message 1 of 8 , May 4, 2014
      Things have been a bit quiet in this group lately, so let me throw this one out there.

      I take an interest in several other vintage machines aside from the Altair, like the Apple II, the early Macintosh and the IBM PC 5150, and for all those other machines someone has created a floppy disk emulator that uses modern compact flash or sd memory cards to store disk images on.  For example the Apple Ii has the CFFA3000, the IBM PC has the XTIDE and one has recently been created for the Macintosh called the Floppy Emu.
         
      We all know the state of floppy disks, they're getting older and new stock is not being produced.  So my question is what's the possibility of a floppy disk emulator for the Altair?  It would be great to be able to load multiple disk images onto an sd card and then make them usable in the original Altair.  I know there's been a fair bit of work done on this site to create Altair disk images.  And those images work well in emulators etc.

      Now obviously one big difference between the Altair and those other machines I mentioned is numbers.  There are way fewer working Altairs around than Apple II's for example, so developing a disk emulator for a very small  market is going to be done more for love than money.  But I thought I would put this out there to see what others think.  Now I don't the skills to develop such a device, but I would be happy to contribute some funding to it.

      Thanks,
      Theo
    • namaman123
      Wouldn t a HxC Floppy Drive Emulator do the trick?
      Message 2 of 8 , May 5, 2014
        Wouldn't a HxC Floppy Drive Emulator do the trick?
      • deramp5113
        Theo, I am about 1/2 through this very project. Unfortunately, it is also my frequently procrastinated project! The project is actually an S100 floppy disk
        Message 3 of 8 , May 5, 2014
          Theo,

          I am about 1/2 through this very project. Unfortunately, it is also my frequently procrastinated project!

          The project is actually an S100 floppy disk controller board, that from the Altair's hardware and software perspective, duplicates the original Altair 2-board FDC. I.e., all original Altair computers and Altair software (Disk BASIC, Altair DOS, Burcon CP/M, etc.) will run without modification.

          On the floppy side of the controller, the FDC also duplicates the original Altair 2-board set so this new controller can be connected directly to an Altair floppy cabinet with the Pertec floppy drives. However, the Altair Floppy cabinets are hard to find and the Pertec drives are not very reliable in their old age. So...

          Enter floppy connection option #2: This controller can connect directly to up to four Shugart 800 or 801 drives (yes, either one) and make them operate identically to the original Altair/Pertec floppy cabinet. Media written on the Shugarts can be directly used in an Altair/Pertec drive and vice-versa. The fact that a Shugart drive is being used is totally transparent. The Shugart drives are still easy to find, typically less than $100, amazingly reliable for their old age, and don't require the buffer boards for interface like the Altair floppy system. Just provide power and drive is ready to use.

          Finally, the third "floppy" connection option is more along the lines of what you are asking for. The board will allow use of a high-speed serial link to a PC running a simple image file server instead of connecting to physical rotating media at all. The performance of the server "floppy" is pretty much the same as the original floppy drive. This allows direct use of any of the disk images we've been archiving recently on a real Altair. It would be a small step at this point to put the image server on a Raspberry Pi or similar piece of hardware instead of a PC, if desired.

          Mike


        • B Degnan
          Mike that all sounds great...I d love to help test if you need a guinea pig :-) Bill ... From: deramp5113 To: altaircomputerclub
          Message 4 of 8 , May 5, 2014
            Mike that all sounds great...I'd love to help test if you need a guinea pig :-)
            Bill


            -----Original Message-----
            From: deramp5113 <deramp5113@...>
            To: altaircomputerclub <altaircomputerclub@yahoogroups.com>
            Sent: Mon, May 5, 2014 10:39 am
            Subject: [Altair Computer Club] Re: Possibility of an Altair floppy disk emulator?



            Theo,

            I am about 1/2 through this very project. Unfortunately, it is also my frequently procrastinated project!

            The project is actually an S100 floppy disk controller board, that from the Altair's hardware and software perspective, duplicates the original Altair 2-board FDC. I.e., all original Altair computers and Altair software (Disk BASIC, Altair DOS, Burcon CP/M, etc.) will run without modification.

            On the floppy side of the controller, the FDC also duplicates the original Altair 2-board set so this new controller can be connected directly to an Altair floppy cabinet with the Pertec floppy drives. However, the Altair Floppy cabinets are hard to find and the Pertec drives are not very reliable in their old age. So...

            Enter floppy connection option #2: This controller can connect directly to up to four Shugart 800 or 801 drives (yes, either one) and make them operate identicall y to the original Altair/Pertec floppy cabinet. Media written on the Shugarts can be directly used in an Altair/Pertec drive and vice-versa. The fact that a Shugart drive is being used is totally transparent. The Shugart drives are still easy to find, typically less than $100, amazingly reliable for their old age, and don't require the buffer boards for interface like the Altair floppy system. Just provide power and drive is ready to use.

            Finally, the third "floppy" connection option is more along the lines of what you are asking for. The board will allow use of a high-speed serial link to a PC running a simple image file server instead of connecting to physical rotating media at all. The performance of the server "floppy" is pretty much the same as the original floppy drive. This allows direct use of any of the disk images we've been archiving recently on a real Altair. It would be a small step at this point to put the im age server on a Raspberry Pi or similar piece of hardware instead of a PC, if desired.

            Mike




          • tkaragiris
            Mike, That sounds great, sounds like an extremely flexible device. All those options should cater for what different people want. You d still be able to use
            Message 5 of 8 , May 6, 2014
              Mike,

              That sounds great, sounds like an extremely flexible device.  All those options should cater for what different people want.  You'd still be able to use the Altair with an 8" floppy but a more readily available drive, that makes great sense.   Being able to use all those archived disk images is what I'd really like to do, so the serial option sounds really good.  The concept has already been proven with the APE emulator which basically uses a pc program to serve disks across a serial link.  I've used it and it works well.  Unfortunately that system is limited to a custom floppy format and custom version of CP/M so you can't really do a great deal with it.

              Great to hear there is some work going on with this and I'll wait eagerly for progress.  Sign me up when it's ready!
            • mfeberhard
              Great topic, Theo. When I started restoring these old machines in earnest some years ago, I was very nervous about the fragility of old disk drives and the
              Message 6 of 8 , May 6, 2014

                Great topic, Theo.

                When I started restoring these old machines in earnest some years ago, I was very nervous about the fragility of old disk drives and the unavailability of critical parts, as well as the difficulty of finding decent media. I started down the path of creating an emulator long before I figured out that there already existed emulators for at least some kinds of drives.

                But the more I got into restoring old computers, the more I came to appreciate the actual hardware - not just an emulation. To me, the various hardware emulators (Altair simulators, as well as disk emulators) are interesting, and are good piece of preserving the history. But they also are a long way from the real thing. Sort of like the difference between a flight simulator and a real plane.

                And so I have been learning how to restore old disk drives too. I've fixed a few Altair (Pertec) floppy drives, several Helios (Persci) voice-coil floppy drives, some Shugart and Micropolis drives, and most recently, an Altair (Pertec) hard disk drive (which is insanely complicated, but at least pretty well documented).

                It's not always easy to fix these things, and has required hunting down documentation, learning how the controllers work, chasing down obscure parts, buying a few tools (like bearing pullers and a press) and fabricating several parts.

                But it's also very rewarding when you bring one of these machines back to life. I really should post a video of the Altair hard disk running. It's quite something to watch :-)

                -Martin
                 
              • tkaragiris
                Martin, It s a funny thing, to me software emulators don t hold interest value for very long unless I have the real machine also. The two software emulators
                Message 7 of 8 , May 7, 2014

                  Martin,

                  It's a funny thing, to me software emulators don't hold interest value for very long unless I have the real machine also.  The two software emulators that I use the most are the Altair32 and miniVMac for the Macintosh.  I think of the emulators as complimenting the real machines rather than replacing them.  As you say the emulator doesn't come close to the same experience as using the original machine.  I mainly use the emulators to prepare software and disk images etc. so I can try it on the real machine.  If I didn't have the real machines, like with so many emulators out there, they don't usually interest me for too long.

                  I think hardware emulators are a bit different.  I agree with you that you should restore vintage machines as far as you can back to the original state of operation with original hardware.  I've done that with most of my machines.  But I find once I've restored a machine as far as I can, the continued use of it depends on how easy it is to use.  A good example is my 5150 pc, it has two fully operation disk drives, but when I'm tinkering with software on it, it's easier to use the compact flash drive than the floppy's.

                  I find that with the other machines too.  The Altair has become much easier to use now that I have a functional rom monitor for it.  The front panel still works but for ease of use and preservation purposes I prefer to use the monitor to enter programs and loaders.  I think the same is true with hardware disk emulators, you may have the real thing but it compliments the original machine to have a practical alternative also.  The Macintosh is a great example, I have around 50 400k disk images, many of which are on physical floppy disks which work fine.  But I can put them all on an SD card and load them effortlessly with the Floppy emu.  This makes life much easier when I'm working on some program for it.

                  Cheers,
                  Theo
                • mfeberhard
                  ... When I am writing code for these old machines, I usually use Notepad as an editor, then assemble it using Digital Research s ASM, running on top of
                  Message 8 of 8 , May 7, 2014
                    :-) I guess I have to agree with you, Theo.

                    When I am writing code for these old machines, I usually use Notepad as an editor, then assemble it using Digital Research's ASM, running on top of Anadisk's 22NICE CP/M emulator (which is running in the DOS emulation on XP, which in turn is running on a Fusion virtual machine on my MacBook Pro :-) )

                    It's nice to have a real editor, and it's nice to have ASM complete assembly instantly. I's also nice to be able to edit and at least partially test my code while sitting in an airport or whatever.

                    When I write CDOS code, I still assemble it on my Cromemco Z-1, though I still usually edit the code on my MacBook Pro. Assembling a decent sized program (such as my XMODEM) can take more than 20 minutes! I do this only because I don't have a CDOS emulator.

                    Martin
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