Hi --
Finally had a chance to tour the PSR-EW410 service manual and produce a write-up:
http://sandsoftwaresound.net/psr-ew410-tour-of-its-electronics/In short, Yamaha updated its internal proprietary processor over previous models in the E4xx series. The new processor is the SWX03 which is faster and contains the USB port interfaces, too. The program/wave memory is larger now, too, allowing more samples and code.
The write-up is pretty nerdy, so YMMV.
The entry-level models all have a very similar internal design.
Have fun! -- pj
