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Thread: Original Tandy 1000 no boot

  1. #21
    Join Date
    Mar 2016
    Location
    Georgia, USA
    Posts
    543

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    Quote Originally Posted by falter View Post
    Okay so I have done some checking around. Voltages from the PSU look good. I see clock signals being divided into correct frequencies ok. But there is no activity between the CPU and 128K ROM. I have light 'snow' on the screen, persistent tones from speaker.

    One thing that is odd.. probing the READY line on the CPU it it is high, however if I hit Reset a random number of times I will sometimes see an inconsistent signal there.

    Presently am trying to understand how the 8284 works and why occasional reset causes it to 'leak' signal onto the ready line, or if something should be there.
    IDK maybe bad capacitors?

  2. #22

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    Keep in mind that in their typical weirdness, Tandy used the stripe on the edge of the floppy cable to indicate pin 34, rather than pin 1. And their floppy drive controller and cabling follows the original Shugart standard, rather than IBM's modification of it which later became the industry norm.

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