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Thread: MM11-E or MM11-F (wanted)

  1. #1

    Question MM11-E or MM11-F (wanted)

    I'm searching for a MM11-E or MM11-F core memory module.
    Would be great if anyone could help me to get one.

    mm11e_core.jpg

    But I was also wondering if DEC or a third party made a quad board alternative back then.
    All UniBus memory boards which I have seen seem to be HEX boards.

    Regards, Roland

    (I know about the UniBone of course... But my question is about the memory from those days...)
    WTB: Case for Altair 8800 ...... Rolands Github projects

  2. #2

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    Are you looking for a complete backplane with boards or just the core module (Hxxx)?

  3. #3

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    Hi Ed,

    I'm searching the backplane and boards.
    No problem if it is defective...

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  4. #4

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    Like this?
    SAM_4672.JPG
    SAM_4673.JPG
    SAM_4674.JPG

    Oops, just saw this is an MF11, not an MS11

  5. #5

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    Hi Ed,

    Thanks. It is a beauty but I'm looking for a backplane which fits in the machine.
    The MM11E is like the picture in my first post. It has boards in slot (B)C-F only.
    To be honest I haven't found any memory modules other then the MM11E which will fit...

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  6. #6
    Join Date
    Sep 2019
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    Quote Originally Posted by Roland Huisman View Post
    Hi Ed,

    Thanks. It is a beauty but I'm looking for a backplane which fits in the machine.
    The MM11E is like the picture in my first post. It has boards in slot (B)C-F only.
    To be honest I haven't found any memory modules other then the MM11E which will fit...

    Regards, Roland
    All core memories I've ever seen for the Unibus have just been a hex board with everything on it, and it just plugged into the normal Unibus backplanes. The MM11, I assume, came with the 11/20, which is really old stuff. I doubt a similar design was made for any newer core memories. Things quickly shrunk to a point where you didn't need a whole, dedicated backplane for this.

    The MM11 really more reminds me of how the old core memories for the PDP-8/E were designed.

    So I really suspect you need to find the backplane and core stacks that was for the MM11, as I don't think anything else exists that would plug in there.

    (Correction, the MF11 (nice pictures) was obviously also using its own backplane, but it did use hex core stack boards, but it's also rather old, around the 11/40 era.)
    Last edited by bqt; October 19th, 2020 at 12:13 PM.

  7. #7
    Join Date
    Apr 2011
    Location
    Brisbane, Australia
    Posts
    564
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    There was a 4KW memory and board set for the 11/15 and 11/20 on eBay a fortnight ago:
    https://www.ebay.com/itm/DEC-PDP-11-...-/333744695091
    I would have liked to have got that one, but it would have been twice as much for me by the time the postage, exchange rate and import tax were factored in.
    My 11/15 had a third-party 16KW core stack DD-11 module which is hex height, but specially designed with clearance to fit the 11/15 and 11/20 where the fans impinge on the last slot.
    I was lucky to pick up another of these last year, would love to find another one. Realistically I would probably be better off spending the money on a Unibone though.
    For further expansion, my 11/15 had a 6' Unibus cable off to a ME-11 memory expansion unit, which is the 5-1/4" high H-909 chassis (ie. slimline 11/05 case) but with the standard 3RU fascia panel attached.

  8. #8

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    Quote Originally Posted by 1944GPW View Post
    There was a 4KW memory and board set for the 11/15 and 11/20 on eBay a fortnight ago:
    https://www.ebay.com/itm/DEC-PDP-11-...-/333744695091
    Very nice, I've saved the pictures. Too bad that there was no backplane with it.

    Quote Originally Posted by 1944GPW View Post
    My 11/15 had a third-party 16KW core stack DD-11 module which is hex height, but specially designed with clearance to fit the 11/15 and 11/20 where the fans impinge on the last slot.
    Very nice! Can you share some pictures of this board? Would love to see it.

    Regards, Roland
    WTB: Case for Altair 8800 ...... Rolands Github projects

  9. #9

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    Had a look in my case with core memory cards, one is an H216 and one is a H217 quad card with green handles.
    The 2 others are a sort of sandwich ones, the core plane is directly connected on the carrier card which has 6 card edges.

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