As I recall, even among TI graphing calculators, the TI-89 et al were vastly better, with their functionality for symbolic computation. Of course, nowadays, we all carry around vastly more powerful computers than any of these in our pockets, yet still standards limp on inertly and TI gets to charge a ridiculous amount for a suboptimal product.
The TI-89 destroyed my ability to do calculus. It was just too easy to plug in a problem and get an immediate answer. Great calculator, but be careful not to depend on it too much.
It sounds like the TI-89 vastly improved your ability to do calculus, to the point where it would be a shock to give up that improvement in ability. I would also say sine tables vastly improved people's ability to do trigonometry, back in the day...
People will often express concern about growing dependent upon these devices, but I am in just the same way dependent upon pen and paper, dependent upon dictionaries, dependent upon Google, and a million other things. In a world where access to automated computation is so ubiquitous, what is the harm in, well, growing comfortable using it?
A million times this. Not only that, the Derive CAS was buggy as hell so a good tutor can set some traps to see if it was you or the calculator doing the work.
I, for one, endorse calculators wholeheartedly. I loved my TI-89, and I truly believe the opportunity to play around with it played a large role in my becoming a mathematician, of the sort which the "Calculators ruin math education!" brigade never acknowledges.
When I was in high school and college, they typically only banned calculators that had full keyboards (e.g. TI-92). I believe I was allowed to use a TI-89 on both the SATs and the GREs.
It's a good product that will last a long time yet. You grab it out of a drawer and use it and put it back. It doesn't require any maintenance past some batteries changing occasionally. And it has buttons, real ones.
It's rarely about power either. Very little in mathematics requires much computational power other than a few joules between your ears. Then you're going to use a computer or CAS anyway.
Apart from having real buttons, I don't see how that doesn't apply to people's phones just as well. Nonetheless, I agree that the TI-89 is a great product. It's also a 16 years old piece of electronics; there's no good reason for it to be as pricy as it is. And the value proposition for the TI graphing calculators which lack CAS abilities is even far worse. The pricing does not seem to reflect a truly competitive market.
