If we define hard drives and optical media as "memory based on periodic rotation" then the technology has been around for generations, in fact, with specific m

If we define hard drives and optical media as "memory based on periodic rotation" then the technology has been around for generations, in fact, with specific materials and mechanisms serving to update the paradigm. Tape, drum memory, magnetic discs, and optical. Periodic rotation trades blows with periodic refresh - tubes, DRAM - and phase-change - relays, core, flash - as the prevailing memory paradigm, with hybridization of features often occuring. Von Neumann wouldn't be too surprised at the memory paradigms in use now, because they haven't changed, even though the implementation has become considerably more sophisticated. But, of course, that can't dismiss the idea that a better implementation is a substantial technical advance either.