FDAPM is an Advanced Power Management (APM) implementation for FreeDOS.

APM itself was developed by Microsoft and Intel around 1992, as a way to provide power management on Intel PCs. However, APM may not be present on more modern motherboards, such as those manufactured after 2000.

Common uses for FDAPM include:

  • Turning off the computer
  • Rebooting the computer
  • Saving power (reducing unneeded CPU cycles)

Turning off the computer

To use APM to turn off the computer, type this:

FDADPM poweroff

Rebooting the computer

To use APM to rebot the computer, type this:

FDAPM warmboot

You can also use FDISK to perform an immediate reset of the computer:

FDISK /reboot

Saving power

On motherboards that support APM, use this command:


Kernel HLT instruction

You can also use the FreeDOS kernel's HLT instruction to save power. The FreeDOS kernel CONFIG.SYS option can be one of these:

To use HLT only when the kernel is waiting:


To also provide INT 2f function 1680 HLT:


To provide INT 2f and tell applications about it:


To try harder to use HLT more often, plus provide INT 2f and tell applications about it: