If you have Windows 98 (an OS with ACPI) you should be able to control the
power management settings via the Power Management icon in the Windows
control Panel. ACPI support is installed on Windows 98 computers if an
ACPI-compliant BIOS is present when Windows 98 is first installed. If an
ACPI-compliant BIOS is installed after the Windows 98 installation, it will
be ignored. Fortunately, Windows 98 still supports APM as well. There is a
FAQ for ACPI on the Microsoft Web site.
In the other hand, most BIOSes that support APM include an option to
enable/disable it under the Power Management option. APM is supported by
both Windows 95 and 98.
APM requires support from both hardware and software to function. However,
the operating system doesn't address the power management capabilities of
the hardware directly. The OS runs an APM driver that communicates with the
various applications and software functions that trigger power management
activities. The APM driver and the BIOS communicate directly, while the
system's APM-capable hardware devices all communicate with the system BIOS,
completing the link between the OS and the hardware. Thus, for APM to
function, there must be support for the standard built into the system's
individual hardware devices, the system BIOS, and the OS with its driver.
With APM you can make power management settings in the BIOS setup as well as
the operating system that can overlap or have conflicting settings.
ACPI is a new standard supported by newer system BIOS software running
Windows 98 and later OS. If both, BIOS and OS supports ACPI, full power
management control can be done by the OS, rather than by the BIOS.
(And excuse me my late answers, I can only send/receive messages using a
modem and a very busy line, so it is usually done after two or three
days...)
Oscar Viņas
University of Camaguey. Cuba.
----- Original Message -----
> Thanks for the very good explanation of this function. I have one of the
> newer ATX boards with Windows 98 installed so it should "Power off"
> automatically. When I first installed Windows 98, the power off function
> did work when I did the Start -> Shutdown. After installing other software
> and doing other initial setup changes, the function has stopped working.
I
> think that during this time, I probably changed some of the APM settings
> somewhere (BIOS, Windows???) that caused the problem. Where should I look
> and what should I change to get the Power Off function working again?
>
> Doug
>
> At 7/24/00 01:22 PM -0400, Oscar Viņas wrote:
>
> >The newer motherboard form factors, such as ATX and NLX, include special
new
> >signals not present in previous Baby-AT or LPX form factors. One of them
is
> >called PS_ON or Power_On (pin 14), the other is 5VSB or 5v_Standby (pin
9).
> >They both can be used to turn the power supply and the system on or off
via
> >software. PS_ON is specially evident when you use it with an Operating
> >System that supports the Advanced Power Management - APM (Windows 95 and
> >later) or Advanced Configuration and Power Interface - ACPI (Windows 98
and
> >later) specifications. When you select the Shut Down option from the
Start
> >menu, Windows automatically turns the computer off after it completes the
> >operating system shutdown sequence. A system without this feature only
> >displays a message that it is safe to shut down the PC.
> >
> >The PS_ON signal is also used to power up the system. In these form
factors,
> >the front panel Power switch doesn't physically control the power
supply's
> >access to the 110v AC power. Instead, the power supply's on or off status
is
> >toggled by a PS_ON active low signal received on pin 14 of the ATX
connector
> >FROM the motherboard. The 5VSB signal on pin 9 is always active whenever
the
> >power supply is connected to an AC power source. The 5VSB signal provides
> >the power for the remote switch on the case to operate while the
computer
> >is off and gives the motherboard a limited source of power even when off
and
> >enabling new features to be implemented such as "Zero Voltage Modem Wake
up"
> >or "LAN Wake up", in which a signal from a modem or network adapter can
> >actually cause a PC to wake up and power on. Another option is the Wake
Up
> >Timer, which wakes up and power up your system at a predefined time for
> >specific application.
>
> >----- Original Message -----
...
> > > How does Windows 98 "know" that the computer is of the ATX form
factor?
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