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Technical 
The BIOS and CMOS
ACPI Explained
Advanced Configuration & Power Interface
Advanced Configuration And Power Interface (ACPI) is a system interface
that provides a standard way to control power management and Plug and
Play functions of the computer hardware. ACPI allows the computer motherboard
to describe its device configuration and power control hardware interface
to the operating system. This allows the operating system to automatically
turn on and off standard devices, such as CD-ROM's, network cards, hard
disk drives, and printers connected to the computer. The BIOS performs
the necessary initialization process and hand over during boot and when
returning to full power mode.
For ACPI to fully function, the device drivers and applications used by
the operating system must be ACPI aware. Certain applications or device
drivers may crash the system or fail to let the system resume to full
power mode. ACPI is part of the SIPC (Simply Interactive PC) specification,
drawn up by Microsoft, Intel and others. OnNow is Microsoft Windows side
of the SIPC specification. Each device attached to the system has a class
specification. If any device does not meet the minimum specification demanded
of its class, ACPI can never work. You can read the White Papers
regarding these specifications, they are of a technical nature and make
good toilet reading (if you catch my drift).
APM - Advanced Power Management
The APM system has several principle flaws:
- Every BIOS has its own power management scheme - there is no consistency
from one machine to the next.
- The reason for a suspend is never known. Did the user press the
standby button? Did the BIOS think the system was idle? Or is the battery
running low? This information is not available but Windows must
honour the suspend even if the system is not idle. It is, therefore,
recommended that the BIOS timers be disabled.
- The BIOS hasn't got a clue about what the user is doing and has
to second-guess their actions by monitoring the interrupts and I/O ports.
Sometimes, the BIOS makes a complete mess of it and either suspends
when the system isn't idle, or doesn't suspend when it is.
- Earlier versions of BIOS APM (1.0 and 1.1) didn't provide any system
capability information. The only way to determine if the machine supported
standby was to attempt to put the system into standby mode. If the BIOS
didn't support standby, it crashed. BIOS APM 1.2 resolves this problem.
- The BIOS knows nothing about USB devices, add-in cards and IEEE
1394 devices. It's possible the BIOS will think the system is idle even
if one or more of these devices is/are not.
Power Management Trouble-shooter:
The Windows 98 CD contains a Power Management trouble-shooter (read the
\tools\mtsutil\pmtshoot\pmtshoot.txt file on your Windows 98 CD, first).
An up to date version can be downloaded from our TotalSupport site by
clicking here.
Other Known Power Management Issues
(Taken From Microsoft Technet)
| To be sure of the best setting
for a motherboard option, suitable benchmarking software should be
used and only one field should have a option changed to properly determine
what difference if any the field makes to the system performance. |
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