What is the full form of APM
APM: Advanced Power Management
APM stands for Advanced Power management. APM is an
application programming interface developed by Microsoft and
Intel to achieve power management. It makes Operating system to
run on the personal computer to interact with any basic
input/output system and attain power management. It controls the
power usage of the system until the system is brought into the
How it works
It uses a layered approached to manage the device. It
contains a device driver to talk to OS specific APM driver. APM
communicate with BIOS and the BIOS sends power management to APM
driver. So the APM driver works as a mediator between the BIOS
and operating system.
States of Power Control
There are five power states in APM:
- Full on State: This state specifies
that high power consumption is on. No power management is done
in this state.
- APM Enabled State: APM system is
enabled and doing work in this state but no power management is
done in some unused devices.
- APM Standby State: This state
specifies that APM is inactive for a short time and the system
comes into that state.
- APM Suspend State: This state
specifies that APM is inactive for a long time and system comes
into that state. It takes too much time to come in enabled state
from the suspended state.
- OFF State: This state specifies that
CPU clock is stopped.