The TI-nspire CX CAS was my first calculator with in integrated CAS, and it was a revelation! I was amazed that a handheld calculator could do symbolic logic, even though the technology goes back to the late '90s. I just never knew that it was a thing. The UI and software for the CX is almost identical to the CX II, though the CX II is more than twice as fast. The touchpad in the middle of the directional button was also improved quite a bit on the CX II. I still use this guy quite a bit, just because it is a special calculator to me. The CAS is not as full-featured as that on either the HP Prime or the Casio fx-CG500, but still powerful as hell. The CX also does not have the third-party support that the TI-89 Titanium has, but is many times faster than it and has the benefit of using a UI that was designed for its form factor.

The pen is an Asvine V200 Titanium M.