PAE turned that very simple fact on its head, and screwed things up royally. Whoever came up with the idea was totally incompetent, and had forgotten all the DOS HIGHMEM pains. There’s a damn good reason why we left the 286 behind, and started using 386′s, instead of having HIGHMEM crap with windows into a bigger physical space.
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So repeat after me: PAE didn’t ever really fix anything. It was a mistake. It was just a total failure, and the result of hw engineers not understanding software.