HP-12C gets 'Entry-RPN' or Error in the QSG?

[Les Bell]

(07-06-2014 02:08 AM)Joe Horn Wrote:  In my famously humble opinion, that's not what the sentence by HP means at all. "The next key pressed" is syntactically after "after entering a number" and therefore means "if the next key pressed after entering a number is an operation".

Are you saying that "entering a number" means "[sequence of digits] ENTER"? Because I think it's just "[sequence of digits]" (I'm ignoring EEX and ., here). In which case, "if the next key pressed after entering a number is an operation", then you didn't press ENTER - because you didn't consider it an option. And as kakima just ably demonstrated, if you did press ENTER, it was for good reason, and it wasn't optional.

For the novice, the confusion probably arises because of the overloading of the ENTER key; it's sometimes used to terminate number entry, and sometimes to duplicate X into Y, and sometimes both. And the distinction requires the introduction of the notion of automatic stack lift, and its disabling by certain operations.

Quote:"Separating numeric entries can be done either by pressing ENTER or by performing an operation, e.g. 2 ENTER 3 + performs 2+3, and 2 √ 3 + performs √2+3."

I'd avoid that word "entries" - too confusing! Rather "Separating two numbers can be done ...". Or I'd approach the question by viewing it from the calculator's point of view: "How does the calculator know when you've finished entering a number? You can either press an operator key, or, if you want to immediately enter the next number, press ENTER to separate them" (or even "press ENTER to copy the first number into the Y register and allow the next number to overwrite X". Yeah, it's wordy, but clarity trumps word count, for the reader. Otherwise, we wouldn't be here.