On C64s with the 8701 chip the dot clock is very irregular, for example the time between falling edge of Phi2 and falling edge of dot clock can vary based on how the 8701/VIC-II were initialized. I suspect this can introduce difficult to reproduce phase-of-the-moon like bugs where something works ...

Hi. Some parts of the visual6502.org website have not been working for quite some time now, for example the Die shots -> others... link.
Who knows if/when this will be fixed? I did not find any contact info on the site itself, and I figured some of the folks behind visual6502.org would be on here ...

Hello world!
Been mostly lurking here for a while and I really like everyone's ideas and musings.
About me: I do something in IT (and have been doing since 1996). My main experience with 6502 stuff is from C64 which I have had since 1986 - recently I have amassed some different variants of these ...

Very nice. These are all loose fragments - is there a comprehensive diagram (svg) of diffusion+poly somewhere? Or else just a die shot that is detailed enough so that it can be verified by nerds that don't have anything better to do?

Bit late to the party.
I don't think anyone mentioned here yet why the noise LFSR magically turns to all-1s when you keep the test bit set.

Each bit in the noise LFSR has three pass transisors, LC (copying the nomenclature that was already used here), that is used to shift in the neighboring bit ...