If it doesn't have an Enter key, it's not RPN

[Michael de Estrada]

(07-15-2015 12:16 AM)TASP Wrote:  My HP80 does not have an 'ENTER' key.

Semantics. HP uses Save instead of Enter on the HP-80, and makes no mention of the 4-level stack in the documentation. Instead it talks about adding machine operations, which are the same as postfix. Basically, HP didn't want to scare financial types, who it regarded as mathematically challenged, and focused more on the built-in functions. Later financial models, such as the HP-22, returned to the Enter key, and documented stack operations the same way as the scientific models.