OK, I peeked inside my PET, and found R12 shorted. And it seems I remember almost nothing about this and would have to start all over to see why I did that.
R12 pulls /INIT up, which can be found at TP7.
What I do know is that somehow I figured /INIT should never go low and some chip is erroneously pulling it low. So by shorting the pullup, I hoped eventually the offending chip would burn out so I could find and replace it. It's been over a year (I think) and it hasn't happened.
Dave, what is /INIT, and does bringing it low cause an IRQ (by way of PIA)? Does Jim's PET even have this signal?
Matt
R12 pulls /INIT up, which can be found at TP7.
What I do know is that somehow I figured /INIT should never go low and some chip is erroneously pulling it low. So by shorting the pullup, I hoped eventually the offending chip would burn out so I could find and replace it. It's been over a year (I think) and it hasn't happened.
Dave, what is /INIT, and does bringing it low cause an IRQ (by way of PIA)? Does Jim's PET even have this signal?
Matt