This other comment here mentions that the chips on the sides (i.e. sides of the grid composite of chips) have access to DRAM: https://news.ycombinator.com/item?

This other comment here mentions that the chips on the sides (i.e. sides of the grid composite of chips) have access to DRAM: https://news.ycombinator.com/item?id=28254892 https://news.ycombinator.com/item?id=28254892