Apple Macintosh PowerBook 150 - Manual (Page 86)

More about automatic sleep
The Battery Conservation slider controls three power conservation features:
system sleep, screen dimming, and hard disk spin down.
m System sleep is a state in which your computer uses only the power it needs
to maintain the contents of RAM (such as any open programs and
documents, and various control panel settings).
m Screen dimming saves battery power by automatically turning off the
backlight of your PowerBook display screen.
m Hard disk spin down stops your computer’s internal hard disk from spinning
when it isn’t being used. If the PowerBook is in sleep, the hard disk
automatically spins down.
The Battery Conservation slider has five settings:
The time it takes for each feature to take effect depends on the setting you
choose. If you drag the slider toward Better Conservation, it takes less time
for the system to sleep, the hard disk to spin down, and the screen to dim.
The table indicates how much time passes at each setting before each power
saving feature takes effect.
Minutes it takes if you choose
Conservation Performance
System sleeps 2 3 6 8 15
Hard disk spins down 1 2 3 6 8
Screen dims 1 2 3 4 5
77 Power Management
The five settings on the Battery Conservation slider
indicate the time it takes for your computer to go to sleep,
the screen to dim, and the hard disk to spin down.