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Thread: Q/Q and Q/CD pinouts

  1. #1

    Default Q/Q and Q/CD pinouts

    I have found a unknown QBUS backplane that was manufactured by Measurex. I can't find any sort of documentation about it except that it is QBUS and will accept standard DEC dual height modules. Unfortunately, that also means that I have no idea whether this is a Q/Q, Q/CD, or a mix of both on this backplane. Included a picture of the front and back below

    I started beeping out the board and I can see that A2 is connected to +5V on all of the slots, and I can see that there are differences between the top 5 rows and the remaining 8 below. There are resistor packs at the end of the first 5, and then again at the bottom of the backplane itself. If I had to guess, the top 5 would be Q/CD and the others would be Q/Q, but I really don't know how to validate that.

    I have found a wiring diagram of Q/CD slots from the peripheral manual, which shows how the Q/CD slots are wired between each other. I can't find the same for Q/Q slots. I did find an old link to a product from Avalon systems that diagrams the Q/Q pins, but it really doesn't go through how they are connected in series.

    My question is this: What is the easiest way to determine what I have here without blowing up boards in the process?

    Measurex-qbus-front.jpg
    Measurex-qbus-back.jpg

  2. #2
    Join Date
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    Default

    I don't think that is QBUs, the two parallel metal bars would prevent QBUS cards being inserted, it certainly looks that way to me from the photo.

  3. #3

    Default

    Thanks for the reply

    IMG_20191106_103610.jpg

    It most definitely accepts QBUS cards, as my dual height cards fit into the slots. There is also wording on the backplane itself that says QBUS.

    The bars in the middle are made of some non-conductive material. It almost feels like fiberglass.

  4. #4
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    Default

    Quote Originally Posted by ccureau View Post
    I have found a unknown QBUS backplane that was manufactured by Measurex. I can't find any sort of documentation about it except that it is QBUS and will accept standard DEC dual height modules.
    Look on eBay for pictures of the boards. They are quad width and that backplane is likely to be very custom, just by how the visible traces are routed.
    A normal DEC backplane have mostly parallel traces, the Measurex sure doesn't look that way.

  5. #5
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    Not convinced, It doesn't look like the quad board goes all the way to the edge. The measurex board does look very similar to a quad QBUS card.

    s-l1600.jpg

  6. #6
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    Quote Originally Posted by PG31 View Post
    Not convinced
    measurex.jpg

    note it is only using the backplane for power

  7. #7

    Default

    Interesting!

    So, if it is the case that the board is too custom, I wonder if it is worth it to desolder the card edge sockets and create a backplane...it would be kinda fun. But I still would need to know how to wire the thing up.

  8. #8
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    Quote Originally Posted by Al Kossow View Post
    measurex.jpg

    note it is only using the backplane for power
    And, the fingers look longer on the Measurex board...

  9. #9
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    perhaps there is more than one qbus

    https://www.qbus.be/en
    Dave
    G4UGM

    Looking for Analog Computers, Drum Plotters, and Graphics Terminals

  10. #10

    Default

    I finished beeping out the slots last night, and here's what I've found so far...

    The upper 5 slots are definitely wired differently than the lower 8. However, for the most part, all pins seem to be wired in parallel (Slot 1 Pin A1 -> Slot 2 Pin A1, etc.). There are some pins that either have no connection, or I wasn't studious enough to find them in other slots. Power was available where I expected power to be, and they all mapped back to multiple screws on the end of the board. There's still a few screw terminals which I haven't figured out what they are for yet.

    Here's what I found:

    UPPER SLOTS
    SLOT A:
    - E1 seems to have a connector to what could be a jumper. Currently it has no connection.
    - K1 and L1 are linked.
    - M2, N2, R2 and S2 have no connection between slots.

    SLOT B:
    - U1 has no connection between slots
    - K1 and L1 are linked

    SLOT C:
    - U1 has no connection between slots
    - K1 and L1 are linked
    - M2, N2, R2 and S2 have no connection between slots.


    SLOT D:
    - U1 has no connection between slots
    - K1 and L1 are linked

    LOWER SLOTS
    SLOT A:
    - S1 and U1 have no connection between slots
    - K1 and L1 are linked.
    - N2 in slot n is connected to M2 in slot n+1
    - S2 in slot n is connected to R2 in slot n+1

    SLOT B:
    - U1 has no connection between slots
    - K1 and L1 are linked

    SLOT C:
    - K1 and L1 are linked
    - ONLY E1, J1, M1, S1, U1, A2, B2, C2, and D2 are connected through slots
    - Remaining pins appear to be unconnected

    SLOT D:
    - K1 and L1 are linked
    - ONLY J1, L1, M1, S1, T1, A2, B2, C2, and D2 are connected through slots
    - Remaining pins appear to be unconnected

    It looks to me like the lower slots are built for quad width QBUS boards, but I am not an expert. I really am not sure about the upper slots at all.

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