Hi there! This is #nakeddiefriday again!
Today I'd like to present you one of frequent sources of pain for C64 owners, the infamous PLA. This is MOS 7700R2. They failed way too often, and considering this is custom silicon, the only option was to get another one of the same.
Many thanks to @root42 for providing this sample!
SiPron link: https://siliconprawn.org/archive/doku.php?id=infosecdj:mos:7700r2
The same but with metal removed. This exposes nicely coloured diffusion and poly features.
A die overview shot. Top to bottom, the products array, the sums array, and the big, big output driver transistors.