If neither of these can satisfy you, you can only choose voyage200, but this one can't be used for SAT and AP exams, and you can only learn by yourself. 89 and CAS are the strong models of TI at present. 89 is mainly aimed at the study of engineering and electronics, and CAS, the latest machine, can basically meet all exams, and those without functions will not be used in exams. For Chinese mainland candidates, the exam is not a problem. Some questions are calculated by hand faster than by machine. You can buy 89 or CAS to cope with the exam. I suggest you buy voyage 200 when you are studying in university. I was shocked to read your message. I didn't expect you to know so much about TI, and every function and deficiency can be subdivided. I guess you are good at playing TI. I hope you can do well in the exam.