The Power Manager controls power to the internal hardware devices of battery-powered Macintosh computers (such PowerBook computers). The Power Manager automatically shuts off power to internal devices to conserve power whenever the computer has not been used for a predetermined amount of time. In addition, the Power Manager allows your application or other software to
install a procedure that is executed when power to internal devices is about to be shut off or when power has just been restored
set a timer to wake up the computer at some time in the future
set or disable the wakeup timer and read its current setting
enable, disable, or delay the CPU idle feature
read the current CPU clock speed
control power to the internal modem and serial ports
read the status of the internal modem
read the state of the battery charge and the status of the battery charger
Most applications do not need to know whether they are executing on a battery-powered Macintosh computer because the transition between power states is largely invisible. As a result, most applications do not need to use Power Manager routines. You need Power Manager only if you are writing a program--such as a device driver--that must control power to some subsystem of a battery-powered Macintosh computer or that might be affected by the idle or sleep state.