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Data General Nova 1200

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    The so-called Real Time Clock on the Nova was not what we think of today as an RTC. It simply provides periodic interrupts, at 10, 100, 1000 Hz or power line frequency. The keeping of time & date has to be done in software. RTC is device number 14 (octal). You'll find a description of it operation in this document:


      Originally posted by Qbus View Post
      That would be great, in the playroom I have facilities for reading, punching or copying paper tape. So just about any source will work within reason. Also have facilities for reading, writing and editing ROMS so I am just about state of the art for 1970
      Paper tape has a unique advantage being it can with care last forever, floppy drives are fairly durable but beyond a point the drives themselves are getting harder to find. A lot of the old first generation MFM and IDE hard drives are still around and work but that’s just the ones that were for some reason put aside and never left on for years on end and somehow the old disk packs in things like the RL and RK drives chug on, can’t say as much for a lot of the modern stuff.
      But paper tape is so simple, no media to decompose or magnetic elements to weaken or special heads to read can see that lasting forever. The only limitation is it’s not practical for large files.
      OK, excellent to know. I'll keep this in mind, as I have a feeling that somehow here, I might come across this in some form. Do you know if the DG Nova at the Living Computer Museum in Seattle was running the correct version of basic? Back when the museum was open, of course. I know it was running basic, and that they loaded it from an arduino-emulator of paper tape when they needed to boot it. Likely, the same Jeff Kaylin created the "arduino-booter" who also developed the modern core memory replacement that I've shared:

      I'm thinking I might be able to get my hands on their code at least, and potentially convert that back into something one of us can punch to paper tape...(which might be where THEY got the code it in the first place, who knows!) But I'm just speculating out on a bit of a limb here so far...


        Originally posted by Nevets01 View Post
        So I follow up on a lead from this very forum about a typesetter's warehouse that had closed down, and the owner was trying to sell some of the contents.
        When I got there, there were two DG Novae, and a Digital Computer Controls D-116. I ended up with the D-116, since he wanted a great deal more than I could afford for the 'genuine' Novae, as well as an ASR-33 teletype and some other odds and ends.
        As it turns out, just a couple days after I left, Glitch came and bought the entire contents of the warehouse (and believe me, it was a LOT) for a large sum of money. And Z bought his Nova off of him. The fact that he posted about a fairly obscure computer shortly after three of them had sold led me to (correctly) suspect that they had come from the same source.
        Very good detective work here! With so few of these machines out there, it only takes a modest amount of hunting & research to put the pieces together like this. I've figured out "what when where" with other vintage stuff using the same logic. It really is a small world in many way.

        Originally posted by Nevets01 View Post
        All three machines were freestanding, not in a rack or any other enclosure, when I got there. If they had been extracted, I have no way of knowing for sure or for certain.
        I'm going to speculate just based on this...that they were not mounted in a singer typesetter like I showed in my pics above, simply because they had front panels. I've only recently become aware of the existance of phototypesetter equipment, because of it's connection to DG Nova/DCC-116s, and the now somewhat infamous Frenchtown NJ auction this past July.

        They of course, could have been mounted in other things yet unknown to any of us *with* their front panels, and someday, that could be fun to see!

        Originally posted by Nevets01 View Post
        Now on to speculation.
        If you look closely at the I/O board that Z got with his Nova, you may notice a rather snazzy logo for a company called "CompuScan". A large nameplate from the same company is present on my Teletype. A couple hours of googling led me to the conclusion that CompuScan was a company what developed early OCR systems.
        Speculation: Z's Nova (and my Teletype, attached to it) was attached to some form of early OCR scanner at some point in its life.
        I can't say whether it was still there or not, I only had a few hours to look around, and I was considerably less savvy at that point. You would probably want to ask Glitch. If anyone has/had it, it would likely be him.
        This is excellent speculation! OCR Scanners have hit my radar a couple of times this year. In historical documentation only, as I have yet to see one in real life...

        This is an example of something that, contextually, should be run by a DCC-D116, mostly because the terminals they show are for the Entrex 480 system, which I KNOW runs off a DCC-D116. Thus my most recent interest and obsession in them...and my journey to the Frenchtown, NJ Auction, but I digress..

        I will reach out to Glitch, just because now you have me curious!

        Thanks again for all this great feedback!



          So by the time I found out about this, a lot of the stuff had been parted out and some of it scrapped. Apparently the original owners had been trying to work with several hobbyists and amateur radio operators for like, two years or something, and had gotten a lot of "definitely interested, will be by to pay and pick up" type of replies that resulted in no action, and had gotten tired of it.

          Most of the DG and Computer Automation stuff was connected to typesetting machines, there were two Kurzweil OCR systems but they were the later integrated packages, not the big early boxes with a full-fledged Nova attached. The Kurzweil stuff may have an OEMed Nova or Nova-compatible board in it, too. I believe they'd told me the Fairchild 2300 (TRW 130, AN/UYK-1...originally a 1950s nuclear sub satellite nav computer) was also hooked up to a typesetter.

          We ended up making a second trip up to pick up some other large things that weren't really shippable -- the remains of at least a dozen Kaypros, the guts out of two Linotron 202s that had gotten scrapped, misc. cables and other bits that had been found since the original pick-up, and a box of board scrap that had come from some of the equipment.

          I suspect CommodoreZ's Nova 1200 was indeed connected to that Teletype at one point, though the Teletype may have shared service between several computers, such as the Fairchild 2300, which also has current loop output. Don't know what the Nova 1200 in particular was doing, though.

          Here's some pictures of the stuff, unloaded in the new building (not everything is from the same lot, in the second picture):

          It pretty well filled the back of the 24-foot Mack box truck:

          There was a bunch of Sun stuff too, which was one of the big reasons I was interested in the stuff (still support it for my day-job). TangentDelta has been working on a lot of the Computer Automation Naked Mini stuff.
          Check out The Glitch Works | My Retro Projects | Vintage Computer Services | Glitch Works Tindie Store -- Vintage Computer Kits and More


            I talked with those people about a year or two back. Really wanted the AN/YUK-1 and for some reason that may border on brain damage I would still love to have one. Just at the time had a lot of other stuff going on and with the cost of that system at that time, think they wanted $500.00 and the distance involved driving all the way up to get it figured that would have set me back another thousand or so by the time gas, hotels and everything else was added was not able to do anything.
            Great to see it went to a good home.


              I'm well overdue to post updates on this thread, so here goes:

              The Nova 1200 is up and running now!

              Step one was verifying that the power supply was operational. I started by reforming the 5 large electrolytic capacitors. The smallest of which was too far gone to be reformed and was replaced, while the other 4 performed well enough to be reinstalled. Initial tests with dummy loads attached to the important power rails resulted in a fuse instantly blowing each time I applied power. The fault was traced to a massive diode bridge rectifier which had a short between two contacts, so it was replaced. After that, the power rails tested good under dummy load, ripple was rather minimal. It produces an interesting squeal when running, which changes based on the load, but apparently that's common for this era of Nova.

              Next, I powered up the machine incrementally with a piece at a time.

              First, the front panel. Success. Then the processor board. Success, but you can only test so much of the front panel lamps and switches with just the processor.


              I installed an 8K core memory board and powered up the system, and after finding the address of the memory, I was able to confirm that I could read and write to memory.

              After that, a friend of mine was fascinated with the machine, and offered to assemble a simple test program to see if the machine was able to actually compute something. We started with a simple jump test, and then moved up to a Fibonacci number calculation test, which it passed just fine. You can watch that in action here:

              With that out of the way, the machine sat for a bit while I sorted out my serial board situation because there isn't much I can do with the machine without practical I/O. The two serial boards I had were either:
              A: not documented in the slightest (the CompuScan OEM multi I/O board)
              B: not intended for use as a primary serial interface (Quad Multiplexer, I suspect it to be a 4063)

              In the meantime, I got my core memory situation sorted out a bit better. I was able to confirm 3 out of 4 8K boards worked fine. The last one produces all 1's on the data bus, but that's a problem for another time. The remaining 3 were jumpered to form a contiguous 24K address space, and installed in the machine.

              I was able to find someone selling a 4075 online, and with help from Nevets01 confirming that it was the correct type of board I would need, I purchased it. I configured it and ran some tests, which indicated that a single transistor in the TTL to RS232 level conversion circuit had failed. After replacing it, I was able to confirm TX from the Nova at 9600 baud -- blazing fast for a 1971 machine! Upon passing the ASCII spam test, I moved onto a serial echo/parrot test, which it passed handily.

              Then it was time for the big test: running single-user BASIC. I toggled in the bootloader to the top of memory (which happened to mostly be there already because core memory), and then sent the Binary Loader over serial. After that passed, I loaded BASIC over serial, and got a prompt! BASIC works well, and the machine is operational! I need to make a video demonstrating BASIC and some glorious blinkenlights next.

              The aforementioned friend who assembled my test code also happens to have written a Nova assembler, which you can find here:

              I created this ( ) page to centralize what I'm doing with the 1200, but I'll try to remember to post updates here more regularly.

              Lastly, I want to thank everyone who helped me get this far, as this was a big deal for me to reach these first major goals for my Nova.
              Current projects: The Cactus 6502 front panel homebrew computer , repairing a DG Nova 1200 (it works!), upgrading an OSI Challenger 4P, fixing a Hero 1 robot, monkeying with VIC-20s, reverse-engineering a Decitek paper tape reader/punch, among other things...


                Very nice indeed; congratulations!

                By "4075 board" do you mean the "DGC NOVA CASSETTE I/O", which is numbered 107-000151-19?

                Could you share more specifics (e.g., files and procedures) about how you set up to load-and-run single-user BASIC?

                I, too, have a Nova 1200 to rejuvenate. Alas, it's missing a power supply so I've a few more preconditions to satisfy than you did :-<.



                  Looks like great progress!


                    Computers: Amiga 1200, DEC VAXStation 4000/60, DEC MicroPDP-11/73
                    Synthesizers: Roland JX-10/SH-09/MT-32/D-50, Yamaha DX7-II/V50/TX7/TG33/FB-01, Korg MS-20 Mini/ARP Odyssey/DW-8000/X5DR, Ensoniq SQ-80, E-mu Proteus/2, Moog Satellite, Oberheim SEM
                    "'Legacy code' often differs from its suggested alternative by actually working and scaling." - Bjarne Stroustrup


                      It is good to see a NOVA up and running.


                        Originally posted by firebirdta84 View Post

                        Qbus, I assume that you're looking for a vintage 50-year-old tape with Nova Basic on it. But in the meantime, what would you think about Nova Basic being punched new/today on a paper tape for you?

                        I don't think that I have the capability to do this yet, but if it would be meaningful to you, I'll keep it in mind with my Nova restoration and build project list for the next year or so...


                        If I had the binary image of this, I could probably do it, although it is a PITA to set up the tape punch and I set it up only a few times a year. I have yellow fanfold and DEC fanfold and roll tape. I have some hybrid Mylar but that is really precious.

                        I made some "fake vintage" DEC labels for the tapes (for my PiDP8I that look (at first glance) like they came from a time machine!


                          Wanted to know where you got a copy of Signal user Basic from? Have been looking for years for that on the Nova platform. Let me know where I can download it or how I can get a copy please.
                          If I can get a copy I can do the paper tape or anything like that just need the code.


                            Originally posted by View Post
                            Very nice indeed; congratulations!

                            By "4075 board" do you mean the "DGC NOVA CASSETTE I/O", which is numbered 107-000151-19?

                            Could you share more specifics (e.g., files and procedures) about how you set up to load-and-run single-user BASIC?

                            I, too, have a Nova 1200 to rejuvenate. Alas, it's missing a power supply so I've a few more preconditions to satisfy than you did :-<.

                            Hi Paul,

                            I too am restoring a DG Nova 2/10. It has a "CASSETTE I/O" board which I was told has TTY and RTC circuitry on it. I am still waiting for a part to get the CPU fully working (AC deposits via front-panel fails currently), but otherwise the system seems to be operational.

                            Unfortunately I have absolutely no information (schematic or description) about the "CASSETTE I/O". Have you got any information about this board?

                            Last edited by thunter0512; October 8, 2021, 06:16 AM.