First-Time Buyers
 
Texas Instruments, since mid-90’s, has introduced various TI-83 series graphing calculators. First, there was the original TI-83. Then, came TI-83 Plus and its Silver Edition. Just like new models of cars coming out each year, TI has made improvements under the hood. If you currently own TI-83 Plus, you will be happy with its capability to do necessary mathematics while you are in college. But, the TI-83 series models been discontinued.

In spring 2004, TI introduced new models among its non-symbolic graphing calculators: TI-84 Plus and its Silver Edition.

As of fall 2006, within the 8x-series form factor calculators, TI-89 Titanium is the most powerful model. But, it is more complex to use. The critical difference between TI-89 series and the rest of the TI calculators is that TI-89 series is capable of symbolic computations, making it one step closer to a computer algebra system (CAS). The screen resolution is much better than its siblings, which helps the display of 3-D graphics.
 
For detailed comparison of different models, refer to this PDF product matrix that lists all current models as of spring 2007.
 

Upgrading
 
If you already own any of the TI-83/84 series calculators and if you are thinking about an upgrade, there are two things to consider: TI-89 Titanium or CAS’s (computer algebra systems such as LiveMath, Maple, or Mathematica) for your computer. Since more people now own notebook computers, portability is not a competing factor. Rather, be certain of what you intend to use either tool for. In terms of costs, any of the above software sets you back by about $150USD.

If your career goal is to become a secondary school mathematics teacher, then your familiarity with TI’s graphing calculators will be a good asset. It will help both you and your future students. Meantime, if you are aiming to be a straight-mathematics (not math-ed) or science major, then CAS’s are the way to go because of their capabilities of processor-intensive computations and full-color 3-D imaging and modeling. No calculator can match the processing power of CAS’s.