That calculator feature is crazy. I've never seen that. Maybe not a bad idea though, especially for the DOS era when running a software calculator wasn't convenient.
Never used that keyboard but I had a Wang keyboard from that era which uses "Alps White" switches - I think. All I really know is that on my 2nd copy of this keyboard, the switches are branded by Alps and the plastic on them is white. I've inferred from the internet that apparently the color means something. I assume my original had the same switches, but I don't think I ever actually saw them.
I typed on that thing for so many years and from a young enough age that it basically became my personal reference of what a keyboard should feel like and what key layout I prefer (unfortunately the layout isn't common). I was never as good with anything else.
I've also tried the Model M. Having had that experience, I'm definitely an Alps guy. I never got used to the IBM and eventually stopped trying to use it.
I think a lot of these late 80s-early 90s keyboards are just obscure and forgotten, but probably loved by whoever had them back in the day. It can be hard to find any info about any specific model.
I tried to find a twin of my old Alps-based keyboard on eBay but it was difficult to find any info. I thought it might have a different OEM branded version (not just Wang) but never turned up anything on that front. I was hoping there'd be some amazing website somewhere with tons of history and family trees and part number cross references for old keyboards like this, but no luck.
I had a saved search on eBay for years. Finally one came up that didn't come with a computer and was reasonably priced. I grabbed it. It's a later revision but basically the same.
Unfortunately the switches are rough/stiff and not pleasant to type on. I know they're not supposed to be like that. One of these days I'd like to replace all of the switches so I can use that keyboard again. It might be a fun project, but I'm guessing that buying that many new Alps switches (if they even make them anymore) is going to be expensive.
Nowadays my typing is pretty clumsy. I'd like to blame the modern keyboard. I'd like to avoid thinking it's my age. But in fact I now think that input lag is a factor. It's partly LCD lag but also the lagginess of modern GUIs and web browsers that all contributes. I don't think the screen keeps up with what my fingers are doing and it throws me off mentally.