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Re: [midatlanticretro] Acquired a PDP-8/E

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  • Kyle Owen
    ... Excellent. Sounds like everything s in good, working order then. I ve run it for a couple of hours, just counting the accumulator, and all seems good
    Message 1 of 91 , May 27, 2013
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      On Mon, May 27, 2013 at 8:12 AM, David Gesswein <djg@...> wrote:
       
      V2 is power good. It isn't a voltage bus. The manual says 3.75-5 is good.
      Its just driving gate inputs to shut down core access when the power falls.
      8/E, 8/M processor maintenance manual volume 1 table 4-7.

      Excellent. Sounds like everything's in good, working order then. I've run it for a couple of hours, just counting the accumulator, and all seems good there. I'll some more extensive diagnostics, particularly with the asynchronous interface, as I have time.

      Here's DEC's official information.
      http://www.pdp8online.com/bklatt/262.png

      Sounds like its the holder and not the fuse. Since your load is low if you
      have inspected it and didn't see any problems you should be ok. I have
      two heavily loaded backplanes and did have that faulure. I put another
      holder in and added an additional 5V power supply for the second backplane
      so I wouldn't be stressing my power supply.

      Very well could be the holder, though it may also be a defective fuse. I swapped the existing 10A out for a 3AB 20A and the heating problem seemed to go away. The holder was getting very hot prior (but not melting hot, apparently), but now it seems just barely warm after several minutes. I don't have any spare 10A fuses, but I may try to pick some up and give a new one a try.

      Kyle
    • Dave McGuire
      ... OS/8 needs a random-access storage device; paper tape won t do it. Magnetic tape drives are *physically* sequential-access, of course, but the TU56 (for
      Message 91 of 91 , Jun 6, 2013
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        On 06/06/2013 12:54 PM, Kyle Owen wrote:
        > That looks like a nice product, but yes, it's certainly expensive. I've got
        > some FPGA background myself, along with several different microcontrollers,
        > so I may see about creating something that will work with my high-speed paper
        > tape interface. That could be considered an OS/8 storage device, yes?

        OS/8 needs a random-access storage device; paper tape won't do it.
        Magnetic tape drives are *physically* sequential-access, of course, but the
        TU56 (for example) is logically a random-access, block-oriented device. (with
        highly variable latency ;))

        > I would
        > have no idea how to go about writing a driver for it yet, but perhaps it'd be
        > in my best interest to start reading up on the commands for the card and then
        > learn more about OS/8. Do you have any suggestions on recommended reading for
        > this?

        If this was a generally-directed question...The book you want for "most
        things OS/8" is the "OS/8 Handbook". It is excellent. Try to find a paper
        copy if you can, but it's available in PDF on bitsavers:

        http://bitsavers.trailing-edge.com/pdf/dec/pdp8/os8/OS8_Handbook_Apr1974.pdf

        -Dave

        --
        Dave McGuire, AK4HZ
        New Kensington, PA
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