As laptop computers gain in popularity the need to extend battery life has
become acute.  And as people become more environmentally aware, we are
seeing a greater need to conserve electricity, even on desktop models.

Laptop makers have been using power-management techniques for some years,
but it has been a haphazard affair, and there has been no way that an
operating system or an application program can cooperate in reducing power

In 1993, Intel and Microsoft announced the Advanced Power Management
specification.  It describes a standard interface that allows the system
BIOS, the operating system, and applications to work together to save

Here's how application programs can become power-aware:

  Use INT 15H 5300H to see of APM services exist; if not forget it.
  Use INT 15H 5301H to inform the BIOS that you are savvy.
  Use INT 15H 5305H (CPU Idle) when you're waiting around for a
keystroke or mouse click or other event.
  Use INT 15H 530bH (Get APM Event) and take action when requested.

See Also: APM API
INT 15H (AT Extended Services)
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About Advanced Power Management