Advanced power management
Advanced Power Management (APM) is a standard for power management methods for personal computers developed by Intel Corporation and Microsoft in the early 1990s. Today practically every modern PC supports it (especially notebooks , which are particularly dependent on low energy consumption). The newer Advanced Configuration and Power Interface (ACPI), which also defines energy-saving methods, has almost replaced it.
function
Conceptually, in contrast to Advanced Configuration and Power Interface , Advanced Power Management provides that the energy-saving functions are mainly managed by the BIOS and the hardware . The energy saving is largely transparent to the operating system .
APM specifies different modes of activity. The higher the mode, the more components of the PC are switched to an energy-saving mode, which saves more energy but also extends the so-called "wake-up time". Often other energy-saving standards are linked to it (for example Display Power Management Signaling (DPMS) for screens and ATA / ATAPI for hard drives), but this is not part of the actual standard.
The following table contains the usual modes of Advanced Power Management.
| Activity mode | designation | description |
|---|---|---|
| "S1" | full-on | Normal operating mode, everything is switched on. |
| "S2" | stand-by | Some devices are switched off, mostly only those that offer a quick wake-up time. |
| "S3" | suspend | More devices are switched off. |
| "S4" | sleep | The contents of the main memory are saved on the hard disk and then switched off. This requires the support of the operating system. (Idle state) |
| "S5" | full-off | Complete shutdown of all components, only the components necessary for restarting remain active (for example the operating switch). (Soft-off) |
There are also options for saving energy in the components by switching them off completely, partially switching them off (for example hard drives , on which often only the motor but not the electronics are switched off) or power reduction (for example on the main processor ; some newer models offer the option of Throttle operating frequency and voltage, which reduces speed and power consumption.)
Switching to a higher mode is often caused by a certain period of inactivity on the part of the user; some computers also offer a special switch. Often a program can also determine the mode, but control is mostly reserved for the BIOS, with a certain influence of the operating system. Basic settings can therefore often be made in the CMOS setup program.
See also
Web links
Individual evidence
- APM V1.2 specification ( RTF file).