You can define custom formulas and functions, somewhat like the HP Solver application. This allows expansion of the base capabilities of Derive so you can do even more powerful calculations. For example, figure 9 shows a second-order differential equation that was solved by functions in the ODE.MTH file. If you have a need to convert kilometers per hour to apples per orange, you can define such a conversion in Derive without a problem. Derive can be run in either graphics or text mode, depending on your preference.
Text mode is faster, especially when plotting, but obviously is far less accurate.
You can use Derive to build complicated expressions and then import them, ready-made, into your programs. This eliminates the need for the two separate executables that the previous versions used. Speedwise, the new version seems about on par with the 3.x versions. In conclusion, if your math needs exceed the built-in capabilities of the 200LX, buy Derive. You won't be sorry.