What does APM mean in your computer?

APM Full name Advanced Power Management, Chinese names advanced management, The latest APM standard, currently 1.2, is a BIOS based system power management solution that provides CPU and device power management and determines when to convert the device to a Low-power state through device work timeout settings.

　　

1. Since APM's BIOS has its own power management scheme, which causes a lack of consistency between computers and computers, each BIOS developer must carefully maintain its own APM BIOS code and functionality.

2. The reason for the system to suspend is not known. Whether the user presses the Sleep button or the BIOS considers the system to be idle, or the battery voltage is too low, the information APM is not known, but Windows must know the cause of the suspension, even if the system is not in an idle state.

3.BIOS cannot know what the user is doing, only by monitoring interrupts and I/O ports to guess the user's activity. Sometimes, the BIOS causes the system to be in a completely chaotic state, suspending the system when the system is not idle, or not entering a suspend state when the system is idle.

4. Earlier versions of BIOS APM (1.0 and 1.1) do not provide any system performance information, and the system supports sleep state only if you attempt to turn the system into sleep mode. If the BIOS does not support sleep mode, it will cause a panic. The BIOS APM 1.2 resolves this flaw.

5.BIOS to USB devices, plug-in computer Accessories card and IEEE1394 device is completely unknown, resulting in the above devices do not enter the idle state, and the BIOS is that the system has entered the idle state, resulting in conflicts, so that these devices can not be used properly or system panic.

Because APM has more than enough, ACPI emerged.

ACPI Universal Advanced Configuration Power Interface, the Chinese name Advanced Configuration Interface, ACPI is designed to address the defects of APM. It defines a number of new specifications:

1.ACPI synthesize a new power management and Configuration Interface specification with existing power management BIOS code, APM application programming interface, PNP BIOS application Programming interface, multiprocessor Specification table, etc.

2.ACPI allows the operating system (not the BIOS) to control power management, which is not the same as APM.

The 3.ACPI standard defines a hardware register, a BIOS interface (including configuration forms, control methods, and motherboard device enumeration and configuration), System and device power status, and an ACPI thermal model.

The code supported by 4.BIOS is not written in assembly language but in the AML (ACPI Machine LANGUAGE,ACPI machine language). The BIOS cannot determine the policy or timeout for power management or resource management.

5. All devices using the ACPI system can communicate with each other to understand each other's usage, are controlled by the operating system, and the operating system knows the state of running systems, so the operating system is in the best position to perform power management.

To sum up, ACPI and APM have many advantages, and it is recommended that ACPI be used to manage the system. The following is a WinXP shutdown problem to further explore the difference between them and their applications. Some people ask why the WinXP Control Panel → Power Options do not have the Advanced Power Management Options page and enable Advanced Power management support options to keep the system from shutting down properly. In fact, the motherboard BIOS that appears after 2000 mostly supports ACPI management, so when the ACPI function in the Power Management Setup is set to Enabled, WinXP has taken over and controlled it.

The APM Option page does not appear on the system, and the Advanced Power Management support option is not available. Most WinXP can be shut down properly, and if the shutdown is not possible because ACPI has a compatibility problem, the solution is to upgrade the latest BIOS files. If not, set the ACPI function in the Power Management Setup to disabled and set the PM control by APM to Yes. Then reboot into WinXP and you will find that the Advanced Power Management Options page (APM) and the Advanced Power Management support option are available in the control Panel → Power options, as long as you check to enable Advanced power management support and in the registry Hkey_local_machinesoftware MicrosoftWindows ntcurrentversion Winlogon Find the Powerdownaftershut-down, and set the value to 1, and then reboot, usually the problem can be solved.