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Thread: What controls the Commodore B128-80 Keyboard? 6525 Tri-Port?

  1. #1
    Join Date
    Dec 2016
    New Jersey

    Default What controls the Commodore B128-80 Keyboard? 6525 Tri-Port?

    I have had awful luck with Commodores recently. I decided to dust off my Commodore B128-80 and she fired right up, except that now for whatever reason the keyboard doesn't work at all. No keys register.

    There is a 6525 Tri-Port interface right next to the keyboard connector on the motherboard, does that read the keyboard?

    If so I am screwed, 6525s are rare as hen's teeth, and I am not confident in my desoldering skills either.

    Could it be anything else?

    Just to recap in the course of two weeks I got a PET 8032 that blows a fuse everytime I turn it on, a Commodore C16 that ran for about ten seconds before its TED chips imploded (or some color ram), and now my trusty B128 has decided to quit accepting my keystrokes! What a week!


  2. #2
    Join Date
    Feb 2009
    Markham, Ontario, Canada


    Yes, correct. The 6525 at U28 controls the keyboard. That chip pretty much does all the work of reading the keyboard, but is also used to control PAL/NTSC selection with a jumper.
    If the machine boots and the cursor is blinking it's very likely that the chip is bad unless you found some way of attaching the keyboard connector backwards.

    WANTED: CBM-II hardware or software, PET software


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