ANDAbout putting the arithmetic keys right or left, however, there was agreement to put them below [ENTER] -- please see also HP's Prime.
Reasons for keeping the arithmetic operators directly below [ENTER] were ergonomic (for right-handed people).
Let's take a look at ALL these portrait RPN calculators after the 41. They are all in the following arrangement a) ENTER left b) Math operators right c) Math operator order top to bottom = [/ , * , - , + ]. The ENTER is not above the math operators on any of them!
28C & 28S
32S & 32SII
48S, 48SX, 48G, 48GX, & HP 48G+
- 33S -- moved ENTER to bottom right, just left of "+"... few people like this calculator. The small ENTER is generally disliked.
49/50 -- moved ENTER to bottom, below "+". The small ENTER is generally disliked.
Prime -- moved ENTER to RIGHT side. Prime has its fans, but it's a whole different beast from all the other calculators.
It has the math operators on LEFT, which hasn't been done since the HP41. But simple keyboard operation wouldn't be necessarily fluid for the fans of the classical layout, either, because the proposed operator order is rearranged from how it was on the old HPs. It's trying to put 1 foot in each camp, which will result it being an ally of neither's fans.
So, why not follow the big list of calculators which people generally like? Was really it ever an ergonomic problem that the math operators were not under the ENTER? This is the first time I've heard that was an issue... so very many HP models were done that way.
To me, the prime consideration should be to not to create an oddball that isn't easy for HP fans to use effortlessly. Either pick the classic (HP41 and earlier) layout in its entirety (including operator order!) OR, what I think is probably smarter, follow the big list above of everything from the HP42S through the DM42. The 43S is envisioned as been a modern successor to the 42, isn't it? Why fiddle with something so critical?