To me, the symptoms described in the lead post strongly suggest that RAM chip U9 is defective. The only faintly puzzling detail is that the KIM, "seems to take a minute or so and multiple resets to settle down." But I imagine a broken bond wire could cause that behavior. Inside the IC's plastic package the actual die would have a no-connect on the A3 input, causing that input to float, and it's plausible that it would take some time to settle down.

-- Jeff

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In 1988 my 65C02 got six new registers and 44 new full-speed instructions!
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