Probably the same sensor as in the 810? I know it is a Sony, confirmed by the Pentax rep. But the Pentax engine may add something special perhaps. I forgot to ask if it has focus peaking in live view, but the K-3 has, so I would think it is on it too.
Good grief, that's 20% bigger than my first ever hard-drive! Mind you, that was thirty years ago. Doesn't time fly?