Unusual non-HP RPN Calculator from Hungary

[rprosperi]

(08-29-2016 01:28 AM)Accutron Wrote:  It's not a homegrown Hungarian 4640 clone. It's just a straight NS 4640 with a partly reprinted bezel. His price is in fantasy land.

This is what I thought, but I definitely don't know the Nat Semi. machines well enough to tell just looking at the pics. What gives this away? Isn't the wavy symbol above the LED window a Nat Semi design?