Sorry if this is the wrong forum, but I wondered if anyone could tell me the functional differences between the FX-991D and the FX-991H. Having looked at photos of the two side-by-side, the keys all look to be labelled the same, so the only obvious difference is cosmetic. If anyone can help it would be greatly appreciated.
For what it's worth, the reason for my enquiry is that I learnt to use my fx-450 and then fx-451m at university in the mid-80s but, over the last few years, I haven't had much of a need for a physical calculator. However that need increased recently and, due to the fragility of my fx-450 and fx-451m, I bought n fx-991esplus. Unfortunately though, I just don't get on with it as I find it awkward to use for my main needs related to base-n conversions (the fx-450/451m being extremely simple to use for that). In fact, I bought a sharp EL-W531 first, but that's just weird!). So, lately, I've been looking at vintage Casio calculators and so far have acquired:
an fx-115s-w - which is a nightmare for base-n due to the [MODE][MODE][MODE][MODE][MODE]1 sequence needed to enter base-n mode)
an fx-115n - which is pretty good, but doesn't have complex number support which looks like it could be useful to me, so I then got
an fx-115d - which I'm relatively pleased with so far.
However I noticed that the fx-991d/fx-991h appear to have the same features as the fx-115d, plus the set of physical constants that I had on the fx-451m, so I was planning to finish off by getting one of those (unless someone can suggest an alternative that includes all of those features PLUS the same sort of ease-of-use and unit conversions on the fx-451 in a more robust form).
Any information would be very helpful.