Thread: Perth PET
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Old 12th May 2022, 9:01 pm   #110
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,586
Default Re: Perth PET

No, there is something fundamentally wrong at the moment, possibly the processor is not really executing NOP instructions but some other instruction instead.

Could you check and report the voltages / logic levels measured on the DA0 pin (pin 30) through to DA7 pin (pin 26). No need to show scope traces as we are expecting steady logic levels imposed by the pullup / pulldown resistors.
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