Hypothetical WP 35S

[David Hayden]

I think there's another option for hardware: Take the 41CL approach by replacing the hardware of some existing calculator.

And regarding RPL, keep in mind that "RPL" is many things: an operating system, an interpretter, a low level language, a high level language, and who knows what else.

For an RPN calculator, the interesting part is the language itself. RPL is very compact, so it may be possible to implement an RPN calculator using RPL in a small footprint.