What is ACPI and its functions and features?

What is ACPI: ACPI Advanced Configuration & Power Interface Contents
ACPI stands for Advanced Configuration and Power Interface, which means "Advanced Configuration and Power Interface ". This is a power management standard jointly developed by Intel, Microsoft, and Toshiba.

What is ACPI and what functions can be implemented:

1. You can enable the peripherals to switch at a specified time;
2. Users who use laptops can specify that the computer enters the low-power state at low voltage to ensure that important applications run properly;
3. The operating system can reduce the clock frequency when the application requires less time;
4. The operating system can allocate energy to peripherals and boards based on their specific needs;
5. When no one uses a computer, the computer can enter sleep state, but some communication devices can be enabled;
6. The plug-and-play device can be controlled by ACPI during insertion.

However, ACPI is the same as other power management methods. to enjoy these features, you must have software and hardware support. In terms of software, Windows 98 and its subsequent products and Windows 2000 provide comprehensive support for ACPI. In terms of hardware, in addition to requiring ACPI to be supported by peripherals such as the motherboard, graphics card, and nic, the power supply of the chassis is also required. When the power supply provides a 5 V voltage to the motherboard, must the power supply be switched over? More than 20 mA can be used to achieve "Sleep" and "wake up" on the computer ".

What are the six statuses of ACPI:

They are S0 to S5, and their meanings are:
S0 -- in fact, this is our normal working state. All devices are fully open, and the power consumption generally exceeds 80 W;
S1 -- also known as POSPower on Suspend), in addition to shutting down the CPU through the CPU clock controller, other components are still working normally, and the power consumption is generally below 30 W; in fact, some CPU cooling software uses this working principle)
S2-the CPU is stopped and the bus clock is disabled, but other devices are still running;
S3 -- this is the familiar STRSuspend to RAM). The power consumption cannot exceed 10 W;
S4 -- also known as STDSuspend to Disk), when the system master power is off, but the hard Disk is still charged and can be awakened;
S5 -- this state is the most simple, that is, all devices, including power supply, are shut down and power consumption is 0.

We usually use the S3 status, that is, the Suspend to RAM is suspended to the memory) status, STR for short. As the name suggests, STR stores all the operating status data before the system enters STR into the memory. In the STR state, the power supply continues to power the most necessary devices, such as memory, to ensure that data is not lost, while other devices are in the off state, and the power consumption of the system is extremely low. Once we press the Power button on and off the host Power switch), the system will be awakened and immediately read data from the memory and restore to the operating status before STR. Memory read/write speed is extremely fast, so we feel that it takes only a few seconds to enter and exit the STR state; and S4 state, that is, STD hangs to the hard disk) the principle is the same as that of STR, except that the data is stored on the hard disk. Because the read/write speed of the hard disk is much slower than the memory, it is not as fast as STR. The advantage of STD is that it can be implemented only through software. For example, Windows 2000 can implement STD on hardware that does not support STR.