Mac OS X 10.5 Help
Using function keys on portable computers
Most function keys on your portable computer serve as specific control keys, such as volume and brightness controls.
However, applications may also assign alternate functions to these same keys. For example, Exposé uses F9 and F10 to perform special actions. If you want to use the alternate function assigned to a function key by an application, hold down the Function (Fn) key as you press the function key.
If you frequently use the alternate function of a function key, you can switch the keyboard so that the function keys perform the alternate function without your pressing Fn. You then hold down Fn to use a function key’s original hardware control function.
To switch the function keys to perform alternate functions:
Choose Apple menu > System Preferences, and then click Keyboard & Mouse.
Click Keyboard, if the keyboard pane isn’t showing.
Select the “Use the F1-F12 keys to control software features” checkbox.
To use the numeric keypad on your portable’s keyboard, press the Num Lock (F6) key. The other letter keys are disabled and only the numeric keypad keys work. Press Num Lock again to return the keyboard to its normal functioning.