You can take my TI-89 from my cold, dead hands. It is dramatically more portable than a laptop, the battery lasts forever, and you'd be surprised how powerful

You can take my TI-89 from my cold, dead hands. It is dramatically more portable than a laptop, the battery lasts forever, and you'd be surprised how powerful it is. Sure, it takes a while to learn how to use it, but once you learn how, you can perform tasks with it extremely quickly. Obviously it isn't as powerful as Mathematica or Maple, but for many things I would argue it is both easier and faster to use. I will agree with you that older TI calculators have bad interfaces, but I think the TI-89 has an interface is quite usable and intuitive.