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imsai 8080 video

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    imsai 8080 video

    I got my replacement IC in today and fired up the imsai again and made a video of it.
    I read the book and they might as well be talking greek to me LOL I really don't know how you built and ran these computers

    If you can tell if it is running right from the video let me know

    Click here to watch imsai8080

    It's doing something but it's hard to say if what it's doing is right without some context.

    I'd start with the basics. Turn it on, reset, deposit something in memory, reset, read it back out and hope it's the same.

    Do this for a few different memory locations and see what you get.

    From there you can find some more stuff out (i.e. do peripherals work, does the PROM work, etc.), but that'll at least prove that the core system is working.
    The Vintage Computer and Gaming Marketplace
    The Vintage Computer


      We actually read the CPA manual that comes with the kit and are starting to understand it a little now.
      But it seems to be failing its test So now we have to figure out why.


        Well, you are close so don't dispair!

        There were a lot of boards in the machine. You might want to try pulling everything but the CPU and one memory card (make sure it's addressed properly) and trying it again.

        Swap out other RAM cards if the first one fails. Bad memory (mine and the computers, actually) has been my S-100 nemesis for years!

        Once you've got that all sorted you can add boards back in to see what else might or might not work.

        Best of luck!
        The Vintage Computer and Gaming Marketplace
        The Vintage Computer


          We tried with just the MPU and RAM board and it does the same thing. Also tried it without the RAM board and it still did the same thing so maybe a RAM problem?
          Something is telling me ram board because it is stuck on 6 in address data and we can't deposit anything into memory.
          I just won a bid for a 64K static board off ebay crossing fingers it shows up because I paid 51.00 for it also hoping it is working.
          And because radioshack carries nothing you need we ordered all replacement parts for the MPU and CPA just in case we fry anymore IC's. It was weird that the Buffer's cost more than the 8080a? For all the parts thou it set us back around another $80.00.
          We watch an altair video of one actually running something we can't find alot of on the internet. It was pretty neat seeing the guy toggle in the code and running it. Crossing fingers we can do that soon and make some VIDEO's for eveyone to watch.


            I agree that something is not quite right there.

            Have you tried plugging a monitor into the system to see what appears on the screen? Is there a coax connector? Do you have a cutter/solos card (one of the chips will have this on it)? That might explain the flashing lights on the bottom left of the video. Make sure the cable connecting the front panel to the processor card is snug, and not cut.

            good luck!

            I am still trying to get mine completely restored as well. I have learned a lot (I am still pretty clueless) about S-100's from my IMSAI, with a lot of assistance from others.
            @ BillDeg:
            Twitter: @billdeg
            Youtube: @billdeg
            Unauthorized Bio



              Have you checked the 3 buss voltages?

              Your IMSAI is very similar to an Altair, except for the CPU board and front panel. You might consider joining the Altair Computer Club at Yahoo groups and reading all of the messages in the archives. I think you'll find a bit of useful info there.
              It's at


                Well I thought I would update everyone here LOL.
                We now have it past the test when turning it on. Just can't deposit to memory . I really wanted that 64K morrow Ram board to work I bought of ebay but it didn't. If anyone has a known working RAM board local to NorthEast CT I could try would be great. Buying broken RAM board's is starting to get expensive.


                  How do you know you're buying broken RAM boards? It sounds to me like you haven't ascertained whether your computer is good or bad.

                  Originally posted by greenmeanie
                  Well I thought I would update everyone here LOL.
                  We now have it past the test when turning it on. Just can't deposit to memory . I really wanted that 64K morrow Ram board to work I bought of ebay but it didn't. If anyone has a known working RAM board local to NorthEast CT I could try would be great. Buying broken RAM board's is starting to get expensive.