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  • vrs42's Avatar
    September 21st, 2020, 01:21 AM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    Well, once I gave up on the routing problem (used the autorouter), making a "modern" PC8E board in the spirit of the old didn't turn out to be so...
    74 replies | 3557 view(s)
  • ftcnet's Avatar
    September 20th, 2020, 10:32 PM
    That looks like a very nice replacement for the DEC G8018 PSU. Can you share any additional details (sources, part #'s, wiring diagram, etc..)?
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 20th, 2020, 02:53 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    Probably true, but then I'd have wasted the 7410 gates, and would probably end up tying off the inputs anyway. There's also a pair of decoders...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 19th, 2020, 02:44 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    I started down that path, but the possibilities for 380 and 384 replacement mangled the layout enough that it seemed the routing would have to be...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 19th, 2020, 02:31 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    Um, yeah, that's about on par with what I had. You are meant to enjoy the PDF of the Eagle drawing, which is much easier to read :-). Near as...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 19th, 2020, 02:26 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    It seems our hapless experiment with extensive cloud seeding has finally managed to cause rain in mid-September. It rained here the other day, and...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 18th, 2020, 04:21 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    I did finish Eagle drawings of the DEC M840K. I haven't decided what to do about a "modern" version yet. I have a number of questions about the...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 17th, 2020, 09:41 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    After the rework, it's connected to the logic that detects the "out of tape" condition on the reader. BTW, there's another tiny bit of rework that...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 17th, 2020, 11:36 AM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    Doug, I do see the cut near BV2, though yours is further from BV2 than mine. Trash got picked up today (yay!). The air quality index is better...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 17th, 2020, 09:59 AM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    Your board looks a lot like mine, except for the sockets and the missing 8881. I see the blue wire near E29; do you also have the cut near BV2? ...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 17th, 2020, 04:52 AM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    A look at http://svn.so-much-stuff.com/svn/trunk/Eagle/projects/DEC/Mxxx/M840/M840Kfront.jpg will show that on my M840K, the capacitor is installed...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 16th, 2020, 07:14 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    Cool suggestions, thanks! I'll start by drawing the DEC board, then think about tweaking it for more modern times. Speaking of which, it appears...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 10th, 2020, 04:14 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    I also thought a 128K board would be cool, and actually did a bunch of work to try and clone the KT8A. I ran into problems as there is quite a bit...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 10th, 2020, 04:09 PM
    vrs42 replied to a thread What did I do to my PDP-8 today. in DEC
    I have taken a hint and created an Eagle CAD project for the M840 :-). I scanned my M840K (took me a while to figure out how to get my scanner...
    74 replies | 3557 view(s)
  • vrs42's Avatar
    September 3rd, 2020, 05:22 AM
    There's often a "dog-ear" near the tip of the metal tong/"ears". I think a round toothpick or the like should shove in there and move the ear...
    6 replies | 232 view(s)
  • vrs42's Avatar
    September 2nd, 2020, 08:32 AM
    If you have the PCB removed, the metal tongs that fit over each of the axle posts are accessible, and you can spring them. Usually the handles (at...
    6 replies | 232 view(s)
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About vrs42

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Beaverton, Oregon
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The PDP-8

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