(33s) Implementation of NOT Function

[Gerald H]

Takes any number N from stack and returns NOT(N).
Any number of absolute value not zero returns zero,
zero returns one.
Preserves stack.

Can anyone find a more economical version while preserving the stack?

Code:

1.    LBL N
2.    STO H
3.    CLx
4.    1-ABS(SGN(H))
5.    RTN

N: LN = 28