Indeed, but I didn't count Motorola's decision there as "24 bits is enough for anybody", because they didn't break anything in the 68000 when they added more bi

Indeed, but I didn't count Motorola's decision there as "24 bits is enough for anybody", because they didn't break anything in the 68000 when they added more bits to the address space (in other words, it was forward-compatible). It was the Heap Manager that broke!