Apple Macintosh PowerBook 180 computers - Manual (Page 256)

Working with an external monitor
This section summarizes how your computer and external
monitor behave when you use them together.
Sleep
The PowerBook will not sleep as long as you are using an external
monitor. The automatic sleep settings will not take effect, and the
Sleep command will not work.
Processor cycling
Whenever you use a Macintosh 16" Color Display with your
PowerBook, processor cycling must be turned on. This keeps the
computer from overheating and allows the battery to recharge.
You will not be able to turn processor cycling off if it is already on.
If you had processor cycling turned off before you connected the
monitor, the computer turns it back on automatically.
If you are using any external monitor, it’s a good idea to leave
processor cycling turned on.
Backlight dimming
The dimming feature in the PowerBook Display control panel
turns the screen brightness down to its lowest level when you
haven’t used the computer for a certain time interval. ( You can
think of dimming as “screen sleep.”)
When dimming is turned on, the screen on the external monitor
also becomes dark. When you move the trackball or press a key,
the brightness is restored on both screens.
Video mirroring
A feature called video mirroring allows you to display the same
image on two screens at the same time. This feature is useful
when you want to do a presentation: you can use the PowerBook
screen to see and control what your audience views on a larger
screen. Use the PowerBook Display control panel to turn video
mirroring on or off.
240 Chapter 14: Expanding Your Computer System