The HP 100/200LX lets you open up many applications at the same time. So, for example, you can press (APPT) and key in an appointment, press (PHONE) to look up a phone number, press (MEMO) and enter some important notes, etc. If you open too many applications, you may run out of memory and be unable to open additional applications.
A quick way to see what is or is not open is to press (&...) to the AppManager screen and press (F8) (List). You'll see the following screen. (Your screen may be a little different, reflecting additional applications you have installed, or built-in applications you have open.)
This screen lists the applications set up in AppManager, tells you their status (Closed or Open) and indicates how much memory they are using. You can highlight a desired application and press (F6) to close it or (F5) to open it. The list also shows the hot key combination used to open the application and comments associated with the applications (notes you can enter by highlighting the application and pressing (F3) (Edit).
Rich Hall Editor, The HP Palmtop Paper