@root42 I could prepare a 27C64 EPROM and try the DesTestMAX and it is indeed very useful! It seems there’s a big problem on the data bus, it fails all bits. I’ll check the support logic. Or maybe it’s the PLA? On the TL866II it tested ok, but maybe there are timing problems that only occur when the PLA is used in the real machine. #Retrocomputing #c64 #repair #DesTestMAX
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In the latest video from Reviving Retro, they diagnose and repair a Commodore 64 experiencing a memory error.

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https://makertube.net/videos/watch/2c9576cb-d11d-4677-a231-502c3c41838a

DesTest Switch - AKA DesTestMax2 - A New C64 Diagnostic From Matt Desmond

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