Advanced Power Management

Advanced Power Management ( APM) is a standard for energy -saving methods for personal computers, developed by Intel Corporation and Microsoft in the early 1990s. Today it supports virtually any modern PC (especially notebooks, which are particularly dependent on low energy consumption). The newer Advanced Configuration and Power Interface (ACPI ), which also defines energy saving methods, but it has been supplanted almost back.

Function

Conceptually, see the Advanced Power Management before as opposed to the Advanced Configuration and Power Interface to let manage the energy saving functions mainly by the BIOS and the hardware. Saving energy thereby extends mostly transparent to the operating system.

APM specifies certain Aktivitätsmodi. The higher the mode, the more components of the PCs are connected into a power saving mode, which saves more power but also the so-called " wake-up " will be extended. Often, more energy saving standards are coupled thereto (for example, Display Power Management Signaling ( DPMS) for screens and ATA / ATAPI for HDD ), but that is not part of the actual standards.

The table below contains the usual modes of the Advanced Power Management.

There are ways to save energy in the components also by powering off, partially off ( for example hard drives, which often only the motor, but not the electronics is turned off ) or power reduction (for example, on the main processor and some newer models provide the opportunity to throttling operational frequency and voltage, which reduces the speed and power consumption. )

The change to a higher mode is often caused by a certain time of the user inactivity, some hosts also offer a special switch. Often a program can determine the mode, but usually is the control to the BIOS reserved, with a certain influence of the operating system. Basic settings can be made in the CMOS setup program therefore often.

Reference

• APM V1.2 specification ( RTF ) file.

• Computer Architecture