I just recieved this functional calculator. It is specialty designed, i.e. it applies to a certain industry.
I don't remember seeing such an HP keyboard mimic (I know the keys have an extra column below the Enter key row) before complete with ENTER key. The clincher is it also has an = key. This was made in the late 80's.
I have sanitized the shifted markings but left the key labels for you as a hint. I will post the actual calculator picture soon enough:
It raises some interesting questions. Any guesses as to:
1 brand?
2 industry used for
3 whether algebraic or RPN or both?
4 has any other calculator got the enter key (other than
the 12 C clones posted below)?