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Thread: PDP-8/M restoration - Jerry Walker

  1. #11
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    I've found the RICM blogs to be very helpful but clearly there is a lot of work involved in taking detailed notes and then transferring everything to the blog. It never gets any easier. I've downloaded the 8/I and 8/E blogs as .pdf files that I can search as needed.

    The videos show a lot more of the actual analysis and test/repair/test process but they are very hard to use as a reference since there is no equivalent to "OCR" for videos - no way to search for a specific bit of information. I've got a stack of 8/M power supplies to repair and I ended up taking notes and writing down part numbers as I watched. I generally go through the videos at 1.5x speed and then go back to specific time stamps for info.

    CuriousMarc now has a wiki that he maintains in addition to his videos but that is even more effort to setup and maintain. He's pretty much gone professional at this point, so really that's a whole different level.

  2. #12
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    Quote Originally Posted by jackrubin View Post
    I've found the RICM blogs to be very helpful but clearly there is a lot of work involved in taking detailed notes and then transferring everything to the blog. It never gets any easier. I've downloaded the 8/I and 8/E blogs as .pdf files that I can search as needed.
    Thanks for the comments on our blogs. We will continue to make the blogs even if we add some videos.

    From watching a lot of technical videos it looks like the better ones involved a lot of video editing and post production to make them look professional. I am not sure that I want to invest the time to learn how to use a video editing program to make nice looking videos. Posting unedited videos from my phone would probably look pretty crappy.

    Quote Originally Posted by jackrubin View Post
    I've got a stack of 8/M power supplies to repair
    We made an LTspice model of the power supply in the DW8E-PC Omnibus Expansion Chassis so we could understand how it works. I think that is the same power supply in the 8/M and in some PDP-11 chassis. We would be happy to share the power supply LTspice model if you want to play with it. We also made LTspice models of the PDP-9 accumulator because it uses more than two voltage levels on some of the signals. That helped our understanding and debugging a lot. Now we are making LTspice models of Wang LOCI-2 boards so we can understand how the BCD encoded registers work and how data is transferred between registers. Some of the register behavior is not obvious when looking at the schematics.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  3. #13
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    @Michael - I'd love to get a copy of your LTSpice model. Please post a link or email to me directly.
    Thanks.

  4. #14

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    Quote Originally Posted by jackrubin View Post
    The videos show a lot more of the actual analysis and test/repair/test process but they are very hard to use as a reference since there is no equivalent to "OCR" for videos - no way to search for a specific bit of information.
    You could use something like DownSub to download subtitle files from many video sites. YouTube will auto-generate subtitles on request, but the more technical things are, the more likely it is that the auto-generator will make a mistake. If you download in SRT format, you'll get the text as well as the time in the video where it appears.

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