4-level stack manipulation on 12c

[Marcus von Cube]

(03-05-2015 11:39 PM)Gerson W. Barbosa Wrote:  Here are the stack diagrams at the end of the fourth step:

Code:


...
HP-12C:

T    0    0    5    0    0
Z    0    0    0    0    0
Y   17   17    0    0   17
X    5    5   17   17    5 

         RND  Rv  ENTER LSTx

Are you sure about the 4th column (after ENTER)? Y should read 17.

In classic RPN, ENTER acts as DUP but disables stack lift. LastX honors this flag and overwrites X instead of pushing the stack up.

On the Platinum it looks like ENTER does not correctly disable stack lift for all subsequent commands, probably only for manual digit entry, not for other operations that return values to the stack like LastX and RCL.

Edit: It's no wonder that the 12C+ and the original 12C are behaving in the same (correct) way. The ARM equipped incarnations are running the original ROM code on an emulated Nut processor. The Platinum, on the other hand, is a complete reimplementation of the 12C spec. Obviously there are some deviations from the original (wanted and unwanted).