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

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  • David Gesswein
    ... I used needle nose pliers to spread the tabs to get them in/out. After I put the new handle in I frequently had to bend them back since they stayed spread
    Message 1 of 91 , May 22, 2013
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      On Wed, May 22, 2013 at 11:37:34AM -0500, Kyle Owen wrote:
      >
      > What's the preferred way to remove and replace the handles? I found the
      > replacement part to be very challenging, particularly when there are
      > handles to either side.
      >
      I used needle nose pliers to spread the tabs to get them in/out. After
      I put the new handle in I frequently had to bend them back since they
      stayed spread too much. It was a pain.

      > Since my system is mostly operational, save most of the bulbs, I think I'm
      > ready to test it out with some real code. I don't really know what I'm
      > doing yet with the machine language. Where's a simple program that I can
      > load that makes the accumulator shift left and right, or maybe just
      > increment? I also need to study up on what the rotary switch settings do.
      >
      http://www.pdp8online.com/pdp8cgi/query_docs/view.pl?id=188

      The first are simple instruction tests. The console print test and echo
      test are good for checking out your console serial port. The visisble
      increment AC test is what it says. The shifting lights will be a good first
      program for learning the PDP-8 instruction set.

      After I get the toggle in and console working then I toggle in RIM, load
      over the console serial BIN, then run the 8/E maindecs, then run focal/basic
      etc. To load basic or focal programs (not the bin tape) over the console
      you will need to either convert reader run to RS-232 flow control or use a
      program that can put pauses at end of line etc.

      > Is the rotary switch supposed to turn 360 degrees, or are the stops broken?
      > I like the fact that it's magnetic reed switch-based than normal silvered
      > contacts. Fancy!
      >
      Yes it doesn't have stops. Later panels went to normal rotary switches.

      > Where can I find the pinout information regarding the serial interface card
      > for RS-232 operation?
      >
      For the serial cable & board see
      http://www.pdp8online.com/pdp8cgi/query_docs/view.pl?id=262
      http://homepage.cs.uiowa.edu/~jones/pdp8/hard8e/index.html
      http://www.pdp8online.com/pdp8cgi/query_docs/query.pl?Search=m8650+m8655&stype=Partial+Word&dtype=Document+Sets&submit=Submit+Query

      Looks like I bought TE Connectivity to make the PDP-8 end
      6-87756-7 contacts
      102387-9 housing
      The housing has a polarizing bump which you don't want. It looks like I
      cut it off. It does have the proper width to fit the housing. I bought that
      back in 2009 so I don't remember why I bought with bump. The earlier
      one I bought didn't have the bump but also didn't have the extra plastic
      at the end so it would go in one pin off. It looks like they do have ones
      that look right such as 1-104482-8 but check width. The 3-87651-5 looks the
      style that I bought that is too narrow.
    • 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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