There's a Miida desktop on ebaby that is billed as RPN and i thought "oh yea". Sure. Another pinhead seller using a buzzword that he heard somehow magically gets higher bids. I looked and at first glance it was just an adding machine logic calculator: i.e. postfix in + & -, prefix in X & /. Then i saw that - only in "Konstant" mode - it would be a type of postfix in multiplication and division too, with a permanently entered number in the X register. Even with my loose definition of RPN, this isn't it. But it is an attempt to take advantage of the ease of RPN's entry system while doing repetitive operations such as a surveyor checking cut sheets. I have seen "constant arithmetic" on old calculators before. I'll have to see if they all work like this.
They saw the reason that RPN is superior but just couldn't shed that silly assed equals key. Like a baby with a pacifier: