NewProb clears the home screen and turns off any user-defined functions or stat plots, thus preparing the calculator for a new problem. As you enter new commands, the old commands and answers scroll up the screen. Try to recreate the screens shown below. If you use a computer, then editing with the TI-89 will seem very natural. By default the TI-89 is in insert mode with a vertical cursor bar.
New text is inserted to the left of the cursor on the entry line.
Try this example. When syntax errors are made, helpful messages appear with diagnostic information. You must press ESC to remove the error message before you can make the required changes. There is also a Mode setting that forces all answers to be approximate. Some menus appear in dialog boxes.