I think these are actually built on 150nm process. Using a modern process like 16nm would command some hefty premiums, and some redesign work. This is what old

I think these are actually built on 150nm process. Using a modern process like 16nm would command some hefty premiums, and some redesign work. This is what old fabs end up manufacturing: high volume, low cost ICs. But you're right about the rest. The segmentation is achieved with fuses and firmware.