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Old 18th Mar 2021, 5:09 pm   #1152
Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 7,675
Default Re: Non-working Commodore PET 3016

I am still most concerned by the lack of any discernible activity on UI10 / UI11 pin 1, without which no data can pass from the system RAM to the buffered data bus.

In addition to Mark's suggestions to chase down the lack of activity on the RAS and CAS lines, could we also, with the NOP test now in place, revisit pins 9 and 11 of UG7 both at the same time so we can see the relationship between the two signals going to those points. I am particularly interested in knowing whether you ever see both of those signals high (~4-5V) at the same time.
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