Also Parisse ? Any relation with Bernard Parisse the author of Xcas ?

Yes, it's me. The giac CAS kernel is already ported to the TI nspire, but it lacks a UI. I believe the easiest is to write the UI in lua, and Adriweb already wrote a lua script using the lua module that demonstrate it works, unfortunately only on OS 3.1, not 3.6. I hope it's easy to fix, otherwise I'll have to write a C(++) UI, probably based on nSDL, so that the code base can be shared with the web interface of giac (using emscripten to convert SDL to javascript). SDL could also enable embedded 2-d graphics in a CAS calculation screen.