Advanced Configuration and Power Interface (ACPI)

What is ACPI (Advanced Configuration and Power Interface)?

ACPI, or Advanced Configuration and Power Interface, refers to an abstract yet flexible interface for the hardware which allows integrating features for power management into a standard in a computer system.

In other words, more precisely, it refers to a specific industry specification created to ensure better power consumption and management in both desktop and mobile computer systems.

Understanding ACPI (Advanced Configuration and Power Interface)

What is ACPI (Advanced Configuration and Power Interface)

ACPI is the typical way to integrate power management features through the different components of a computer system, including:

This particular interface helps the computer system to turn on a wide range of peripherals and ACPI compatible devices connected to it, including but not limited to the following:


The primary goal of the ACPI involves the current configuration and power standards of the hardware devices, with specific focus on three key areas, such as:

From a technological point of view, this interface allows the computer to activate the peripherals to activate the computer system, and vice versa.

For example, when you insert a disc into the CD-ROM, it would automatically activate the display and the sound system.

Another significant feature of it is that, when the computer goes into hibernation or in a deep sleep mode, the contents of the Random Access Memory (RAM) are copied to an image file. This file is stored on the hard drive.

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When the system is turned back on, the image file is loaded again. This eliminates the need to reboot the computer every time and open the applications you were working on.


The ACPI specification was launched for the first time in December 1996 as a platform-independent interface created for:

Initially designed by Intel, Microsoft, and Toshiba, HP and Phoenix also accompanied them later.

As a result, over time, the standard was improved even further, and today the ACPI usually has a much larger scope which involves different aspects such as:


The new standards are better than the earlier ones, offering a crossover from them to support all ACPI-compliant hardware fully.

These standards substitute the Plug and Play (PnP) BIOS and multiprocessor specification to offer power to Operating System Power Management (OSPM).

With proper support from the operating system, then ACPI offers the following possibilities:


There are some requisites to make the ACPI work. The most important one is that it should be supported by the following:


You may choose one or more power schemes, and within them you can also control the power supplied to the individual peripheral devices.

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The working process of the ACPI involves the following steps:

Based on the information received, the operating system dispenses power to the components as and when needed.


However, the ACPI may not always work as well as it should, due to some issues in two specific areas, such as:

These error signals are usually indicated by a red or blue screen along with a distinct error code.

Usually, in Windows 98, especially, a red screen denotes issues in the computer BIOS or hardware that results in an ACPI error.

In such situations, you will need to make sure that your system is equipped with the latest Basic Input Output System (BIOS) updates and hardware drivers.

On the other hand, a blue screen would indicate a software issue or any other hidden issue that may have caused an ACPI error.

In such situations, it is needed to make sure that the computer system has all the newest software patches for the operating system and programs.

What is the ACPI Specification?

The ACPI specification describes the structures of the interface as well as the mechanisms needed for designing power management directed by the operating system.

It also talks about the architectures for a more advanced configuration. In simple words, the ACPI specification is the key element of the OSPM.

For example, the ACPI 6.5 specification specifies that it will offer the following:

Different ACPI versions have different specifications and are applicable to all classes of computers, and are also adaptable to the new devices and IoT platforms.

The ACPI specification also includes four different power states, also referred to as modes or Global States, that control the supply of power to each component of the computer system. These are:

There are different Sleep states as well within these Global states, such as:

Each of these states indicates different actions and their consequent effects on the power utilization and management. For example:

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Ideally, to put it in simple words, the ACPI is a standard that defines how exactly different parts of the computer should correspond for power consumption.

It includes different allied aspects of hardware and software programming, bus configuration, as well as a combined standard for power/device interaction.