Hi. I'm going to university in a month to study Electrical Engineering.I already have an TI83 + , but i'm thinking of upgrading to a TI 89 or TI Nspire CAS CX because they both have CAS. Now from what I've read on the Internet the Nspire CAS seems better because of the higher resolution color display and more user friendly interface. However TI89 has been here for a long time and has more applications like EE-Pro, EE200 or ME-Pro. Seeing that i don't intend on programming myself will this be a letdown? Also the TI89 uses AAA batteries which I think is better because they're found easier than the TI Nspire rechargeable battery (especially since I live in Iran and the sanctions and ...you know the rest) . I was wondering if any of you have worked with EEpro or MEPro and do you find these to be a big enough advantage to go for the TI89?