I should also point out that compared to the 3 HP calculators, the WP34S has a comparatively massive flash storage space and unlimited labels for programs.
As a design worthy of the 21st century, there is a very powerful assembler/dis-assembler that allows you to write your programs using a text editor, compile them, load them into the WP34s emulator for testing and then transfer them to the calculator over the serial cable .
The serial cable is the only 20th century part of it :)