A new application has been upploaded to the App Store. Access RPN is free and and shows how RPN works by showing the numbers moving up/down the stack.

It is an intuitive application and very appealing to use.

Active RPN has more functions, programming ability and costs, but I haven't tried this yet.

Access RPN and Active RPN webpage

Nigel

Hi Nigel!

Thanks for the link. I downloaded it just after having read your thread.
It's a nice calc, and more to say it also has a nice design, but to my opinion, what makes it remarkable is the stack, visible and living!
Kind regards.
JM.