PATHDocumentation > Hardware > Power Mac G4 Developer Note


Power Manager

The Power Manager has been redesigned to reduce power consumption in Sleep mode. The latest version, Power Manager 2.0, is a native Mac OS manager designed to implement common power management policy across all Macintosh models by means of the new Power Plugin component.

With the Power Manager 2.0, the secondary PCI bus can be completely powered down, including the PCI bridge. To support this feature, power management support has been added to allow the Expansion Manager to install sleep/wake routines that save and restore configuration header information for PCI devices. Developers of PCI drivers should update their software to include power management sleep/wake callbacks to save and restore their PCI card state on sleep/wake.

IMPORTANT

PCI-bus power is normally turned off in Sleep mode. Any PCI card that does not support the new power management architecture will prevent the computer from turning off PCI-bus power in Sleep mode.

With the new power management architecture, the following states are defined:

Although the current public Power Manager interfaces will be maintained for application compatibility, this is a major revision that may affect developers. Information about the API changes for Power Manager 2.0 is available in a technote, which can be obtained from the website at

http://developer.apple.com/technotes/


© 1999-2000 Apple Computer, Inc. – (Last Updated 15 Feb 00)