> And if you need a TI-89 to stop you from adding meter to ohms, then I don't know
Don't knock it until you've tried it. Though as usual, the HP calculators that have this capability (48/49/50 series and 28 series) have a better UI for using units. But either way, this is a form of type checking, which is pretty universally regarded as a useful and worthwhile feature in programming languages. It catches mistakes from errant keystrokes, lowers the cognitive load by not requiring you to keep track of how many places to shift the decimal point when converting between metric units and obviously makes things a lot simpler when non-metric units creep into your calculations (because you can directly add feet and inches without problem), and encourages proper labeling of units for the quantities you end up writing down.
Ok, I'm from europe, so I never had to deal with inches and feet. I also have all my calculators in engineering mode, because I have often very large and very small numbers (electronic). But that also depends on for what you use your calculator. I have an HP50g but the units menu is something I tryed in the beginning and think at least for me is not useful. And yes, an HP50g would be more like an TI-89.
Don't knock it until you've tried it. Though as usual, the HP calculators that have this capability (48/49/50 series and 28 series) have a better UI for using units. But either way, this is a form of type checking, which is pretty universally regarded as a useful and worthwhile feature in programming languages. It catches mistakes from errant keystrokes, lowers the cognitive load by not requiring you to keep track of how many places to shift the decimal point when converting between metric units and obviously makes things a lot simpler when non-metric units creep into your calculations (because you can directly add feet and inches without problem), and encourages proper labeling of units for the quantities you end up writing down.