Power management keys

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Power management keys placed in the top row, with the keys at that place and below moved down one row.

The power management keys are three keys on a computer keyboard which control the computer's power management status. They are the Power key, the Sleep key, and the Wake key.

The Power key is used both to power on and to power off the computer. Powering on the computer brings it to ACPI state G0 Working. Powering off the computer brings it to ACPI state G2 Soft Off.

The Sleep key is used to put the computer into ACPI state G1 Sleeping from ACPI state G0 Working.

The Wake key is used to put the computer back into ACPI state G0 Working from ACPI state G1 Sleeping.

[edit] Keyboard layout

The placement of the three power management keys on a computer keyboard varies depending on the keyboard's model.

Ideally, these keys should be placed far enough from the rest of the keys, since the consequences of accidentally pressing one of them while using the computer (with the exception of the Wake key, which does nothing in this situation) can range from being annoying to causing data loss. For instance, if the user has edited a file, but not saved it yet, on some applications shutting down the system (which happens when a finger slip hits the Power key) can easily lose all the changes. While the results of wrongly pressing the Sleep key aren't as extreme (unless the computer has problems returning from sleep), it can cause problems in real-time games or any application which depends on a network connection.

One common placement for these keys is in the right of the top row of the keyboard, replacing the Print Screen/SysRq, Scroll Lock, and Pause/Break keys, which are moved one row down. This results in moving the whole 2x3 block of navigation keys and edit keys down one row, occupying the empty space just above the Arrow keys. This annoys some people, because it confuses their muscle memory.

Another common placement for these keys is just below the Delete, End, and Page down keys, in the empty space just above the Arrow keys. When used with normal-sized keys, this can cause a high probability of accidental keypresses, especially when the typist is used to a keyboard without any keys on that position, or with the alternate arrangement described above. This leads some people to physically remove the keycaps. Some keyboard models avoid this problem by using keys with a lower height and requiring a higher force to be pressed.

Many keyboards have found a solution to this problem, in that a specific key has to be held down while the power management key is pressed. Often, this is found in the top-right of the keyboard, to the right of the lock button lights, and can be described as "opposite the escape button". With this button, the power, sleep, and wake keys don't do anything when pressed alone, and the function key does nothing, either.

Most of the original (beige) ADB Apple Macintosh keyboards had a key to turn the machine on and off in lieu of a physical power button on the computer itself, with a symbol on it resembling a right-facing isosceles triangle (▷). It was located at the extreme upper-right corner, above the function keys and above the right most key, or in the same vertical position and in the center.

[edit] References

• Keyboard Scan Code SpecificationDOC