There have been a few research OSes designed around a concept of "all memory is persistent". Iirc this allows some simplifications. For example, no need for a f

There have been a few research OSes designed around a concept of "all memory is persistent". Iirc this allows some simplifications. For example, no need for a file system: the copy-from-disk-to-RAM is pointless when there's no difference between RAM & disk. This didn't catch on as the tech to make it practical wasn't there. And existing OSes were 'good enough' due to memory-mapped files, smart caching techniques etc. Plus boatloads of software using that. But if all background storage were treated as one giant RAM, I could see some cloud/AI big boys crossing that 64-bit size boundary. Or some science/engineering projects like CERN. That said: it's the apps, really. If OS + biggest app working sets easily fit in a 64-bit address space, then why throw 2x the bits at it? And disk <-> RAM transfers (+filesystems, cache etc) are a solved problem.