Or Newton OS devices from 1993. This isn't the first time that Apple has tried to build a computer with seamless state persistence and without a traditional exposed file system.

That said, neither Palm OS or Newton OS could multitask. Android and the iPhone OS seem to have found a very elegant approach to that particular problem without compromising the user experience.

Actually, both of them could, but just in very limited ways.

The Palm had 4 threads, only one of which was available to the developer. Another was used for comms and a third for graffiti processing. I don't think the last one was allocated.

The Newton had at least two threads -- comms in the background were needed even in those dark ages.