[Someone]

> where you had to test for page not present yourself.

I would think that implies you need calls “lock this page for me” and “unlock this page for me”, as using a page after getting a “yes” on “is this page present?” is asking for race condition problems.

That would make this conceptually similar to the Mac OS memory manager, with a difference that didn’t use pages but arbitrary sized memory allocations (https://en.wikipedia.org/wiki/Classic_Mac_OS_memory_manageme...)