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Thread: "Building a 32K RAM Board for the PDP-8/e" article published on Tronola.com

  1. #11

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    Quote Originally Posted by Lou - N2MIY View Post
    Steve,

    Very nice article. Yours looks a lot like mine : http://www.vintage-computer.com/vcfo...chmentid=12029 which I built earlier this year, and the older one http://www.vintage-computer.com/vcfo...achmentid=2430 that I built in 2008. The ones I built were designed by Charles Dickman in 2006, but I had a bit of troubleshooting to do. Chuck's work is here: http://www.chdickman.com/pdp8/ under the "hardware projects" section. The marked up schematic scans are my handiwork. I learned how the omnibus worked to do the troubleshooting from Volume 1 of the 8/e maint. manual.

    Lou
    Greetings everyone,
    I'm a new member just starting out on a pdp8f restoration. I'm thinking of building a new memory card to help trouble shoot the system and found this thread. I cannot access the linked photos by Lou, can anybody help me to find them please? kind regards, David

  2. #12
    Join Date
    Apr 2013
    Location
    Silver Spring, MD, USA
    Posts
    335

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    Quote Originally Posted by djrm View Post
    Greetings everyone,
    I'm a new member just starting out on a pdp8f restoration. I'm thinking of building a new memory card to help trouble shoot the system and found this thread. I cannot access the linked photos by Lou, can anybody help me to find them please? kind regards, David
    The site was rehosted, and you'll need to rewrite the URLs, like this:

    http://www.vcfed.org/forum/album.php...chmentid=12029

    Good luck with your new project!

  3. #13

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    This one works nicely in my PDP-8/e.

    http://so-much-stuff.com/pdp8/32KOmnibus/32KOmnibus.php
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  4. #14
    Join Date
    Mar 2008
    Location
    Westchester County, NY
    Posts
    1,256

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    If anyone ever does another run of Steve or Vince's boards, I'd like to know. Now that I have another 8/a, it would be good to juice that one up to 32kW also. However, I am not so inclined to wire-wrap yet a third board like the other two I did previously.

    Lou

  5. #15

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    anders_bzn made a run for 10 cards but as far as I know they are all gone now. He made a small change on the board and moved the battery holder so that it dosen’t interfere with the card guides. Check with him to get the updated gerbers in case you would like to do a new run of PCBs.

  6. #16

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    As Mattis wrote, all boards are gone. I guessed that I could sell some of them here, but the rumor about them being made sold them really quick. If I had new that there where such a high demand for them I have made more...

    In my 8A/100 write up I mention them: https://www.pdp-9.net/pdp-8a-100 and I also published the gerbers there: https://www.pdp-9.net/docs/pdp-8a-10...ibus-fixed.zip
    Last edited by anders_bzn; June 10th, 2018 at 11:46 PM.

  7. #17

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    We should do another design that includes the KT8-A in an FPGA and 128k of RAM on a quad board. Maybe add some serial ports in the FPGA too.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  8. #18
    Join Date
    Mar 2008
    Location
    Westchester County, NY
    Posts
    1,256

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    Quote Originally Posted by m_thompson View Post
    We should do another design that includes the KT8-A in an FPGA and 128k of RAM on a quad board. Maybe add some serial ports in the FPGA too.
    Ok, if you're going to go that far, how about add an FPP8-A?

    Lou
    Last edited by Lou - N2MIY; June 11th, 2018 at 03:51 PM.

  9. #19

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    Quote Originally Posted by Lou - N2MIY View Post
    Ok, if you're going to go that far, how about add an FPP8-A?

    Lou
    With a big enough FPGA we could emulate any peripheral.

    I used a MicroSemi SmartFusion FPGA/ARM-3 to emulate a PC8-E and the reader. It was much faster than the real one. The same hardware could be used to emulate any non-data-break peripheral. There are enough unused pins to add data-break.
    Member of the Rhode Island Computer Museum
    http://www.ricomputermuseum.org

  10. #20

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    There are so many possibilities here with FPGAs and CPLDs....

    I have a recently built prototype that aims to implement 32Kx8 RAM with just 3 chips. It is just a re-implementation of Steve Lafferty's design (as implemented by Vince a few years ago). The only IC's are the two 32Kx8 RAM chips, plus an EPM7128SLC CPLD. The CPLD provides glue logic and bus interfacing.

    It has a bug I still need to find time to track down... It works fine when accessing memory (read or write) through the front panel, but does not work reliably when the 8/e is running.

    If anyone wants to see the PCB, schematic or Verilog code, let me know. Even better, if anyone has time to help hunt down this bug, I'm happy to ship a prototype PCB free of charge (and free shipping!).

    Malcolm.

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