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

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  • Kyle Owen
    ... And I suppose it s safe to assume that all incandescent bulbs are of OL-2 type? I ve found that the extended memory address lights and the run light are
    Message 1 of 91 , May 22, 2013
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      On Tue, May 21, 2013 at 11:09 AM, David Gesswein <djg@...> wrote:
       

      The 8V doesn't go to the backplane. Its the bulb power that connects directly
      to the front panel. I'm not at my documentation but from memory the grey
      wire to the backplane is power good.

      Your 5V is a little higher than I would expect. It will drop some under
      loading. Also the contacts and 1/4" quick connects tend to get high
      resistance. Either clean or wiggle them under load and if the voltage changes
      give them more attention. The 5V fuse holder melting is also a known problem.
      With your lightly loaded system it should be ok.

      And I suppose it's safe to assume that all incandescent bulbs are of OL-2 type? I've found that the extended memory address lights and the run light are all OL-1, and thus light very dimly. I plan on ordering (50) JKL 7371 12V 40mA bulbs, which, being extra bright, should look good and last a while at 8V.

      The 9-pin (I think) connector going from the power supply to the backplane has a broken tab that holds it to the panel of the power supply. Do you have a part number for these? It makes plugging in the connector quite difficult, since it wants to slide inside the case.

      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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