I’m somewhat aware that Texas Instruments enjoys some kind of quasi-monopoly on high school graphical calculators in the USA. However, when I was taking IB Math

I’m somewhat aware that Texas Instruments enjoys some kind of quasi-monopoly on high school graphical calculators in the USA. However, when I was taking IB Maths Higher way back in 1999, I was using a Casio. Right after that I bought a HP 49G when I went to university. More recently I’ve been using an HP Prime (which I adore, but it’s a bit of an overkill in many ways) and the NumWorks with Epsilon (which is underwhelming in other ways, principally the CAS and lack thereof/need to use a separate and rather clunky interface for Xcas).