POWER.EXE and Advanced Power Management (APM) Support (96560)
The information in this article applies to:
- Microsoft MS-DOS operating system 6.0
- Microsoft MS-DOS operating system 6.2
- Microsoft MS-DOS operating system 6.21
- Microsoft MS-DOS operating system 6.22
This article was previously published under Q96560 SUMMARY
You can install the Power program (POWER.EXE) even if your BIOS does
not support the Advanced Power Management (APM) specification. After
you install POWER.EXE in the CONFIG.SYS file, the POWER command
(without any switches) provides status information.
On systems without APM support, POWER displays the following:
Power Management Status
-----------------------
Setting = ADV:REG
CPU: idle 90% of the time
On systems with APM support, POWER displays the following additional
information reported by the BIOS:
Power Management Status
-----------------------
Setting = ADV:REG
CPU: idle 90% of the time
AC Status: OFFLINE
Battery status: High
Battery life (%): 90
MORE INFORMATION
POWER.EXE detects whether your system has an APM-compliant BIOS and
then adapts accordingly.
When POWER.EXE detects that your system is idle, it saves power by
issuing a CPU HALT instruction. HALT stops CPU execution until the
next hardware interrupt occurs (this is usually the timer interrupt,
which occurs 52 times per second). On systems without an APM-compliant
BIOS, testing reveals a 5% power savings.
If your system has an APM-compliant BIOS, POWER.EXE communicates with
the BIOS. Depending on the frequency of the idle signals from POWER,
the APM-compliant BIOS can save power by shutting down the display or
hard disk, switching the processor to a slower speed, or suspending
the system entirely.
| Modification Type: | Major | Last Reviewed: | 11/19/1999 |
|---|
| Keywords: | KB96560 |
|---|
|