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  4. » Bally mpu conversion to 2732's...connect e12 to e9 ?
(Topic ID: 284459)

Bally mpu conversion to 2732's...connect e12 to e9 ?

By T-Tommy

3 years ago



Topic Stats

  • 5 posts
  • 4 Pinsiders participating
  • Latest reply 3 years ago by T-Tommy
  • Topic is favorited by 1 Pinsider

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    Bally 2732 jumpers e12 to e9 for ground (resized).jpg
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    #1 3 years ago
    OP
     
    ???

    T-Tommy

    Pinside+ Frequent

    US Prescott Valley, AZ

    7y 36,300 158 5

    I've been connecting e12 to the ground plane. I saw this pic with e12 connected to e9. I don't get continuity between e9 and ground. I'm a little confused.

    Bally 2732 jumpers e12 to e9 for ground (resized).jpgBally 2732 jumpers e12 to e9 for ground (resized).jpg
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    #2 3 years ago
     
    ???

    JethroP

    Pinside+ Frequent

    6y 101K 3,132 9 14 1

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    #3 3 years ago
     
    AMS

    barakandl

    nvram.weebly.com

    12y 132K 10,417

    The roms have two enables and both do not have to be used. Saves some power by using both enables versus one forced to ground, but it works either way. Pin 18 and 20.

    pasted_image (resized).pngpasted_image (resized).png
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    #4 3 years ago
     
    PIP

    Quench

    Pinside member

    8y 114K 8,036

    OP
    Quoted from T-Tommy:

    I saw this pic with e12 connected to e9.

    I created that picture.
    I hated the idea of running a long wire from E12 to ground. When I checked the schematics and mapped the U2 ROM address space, tying U2 pin 18 (E12) to address line A11 (E9) made logical sense and looked more elegant.
    Low and behold it was already official:
    http://www.planetarypinball.com/mm5/Williams/tech/bally_read1st.txt

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    #5 3 years ago
    OP
     
    ???

    T-Tommy

    Pinside+ Frequent

    US Prescott Valley, AZ

    7y 36,300 158 5

    I looked at that a couple times but didn't notice it. Thanks for the explanation.

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