I wonder what the viability of a similar OS would be on the nSpire platform, which is fully ARM-based IIRC. nSpires have some very nice options for mathematical

I wonder what the viability of a similar OS would be on the nSpire platform, which is fully ARM-based IIRC. nSpires have some very nice options for mathematical programming (the CAS being a standout feature) but as far as I know lack anything like this. (Most of the advanced nSpire dev is done on a french-language site that I can't fully understand through Google Translate). That said my nSpire CAS CX is pretty kitted out even in the TI Kernel with overclocking, file readers, etc. It even runs Doom! I'm actually amazed that the SAT allows nSpire CAS calculators on their tests (The ACT does not). Apparently the SAT's defining factor for approval is a non-QWERTY keyboard to prevent note input, despite the fact that the nSpire platform allows notes to be transferred to the calculator even before you sideload third-party utilities onto it. The CAS system also allows pretty much any problem to be solved without complex problem manipulation. Most SAT tutors urge students not to solve algebra on calculators because they invariably make mistakes when transforming functions for solver(), but the nSpire's algebra functions will do all kinds of transformations and solve multi-equation functions without much work. You could even solve a lot of geometry problems with the (built in!) geometry program if you forget theorems, and a little competence with things like modulus will take care of the rest of the test without any human computation (though this is slower than solving on your most of the time)