Free42 NSTK ENTER behavior

[Peet]

(10-15-2021 06:01 PM)squid2 Wrote:  .. in 4STK mode, you'd have a leftover 21 on the stack due to running out of stack space and quirks of the 4STK ENTER behaviour.

That is no quirk but well documented, wanted and correct behaviour of RPN. It is based on the function of the T-register and is explained in almost every RPN documentation. You can find this explained in detail e.g. in the manual of the HP35 (from 1972) and in the manual of a brand new HP-12C Platinum from 2021.