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After thinking about it for quite some time, I cannot figure out what process intercepts the click of the mouse or press of a key to bring a sleeping computer back to life.

You can control what devices are allowed to to wake the computer via the device manager, so I would think the process resides in the OS, but if that is true, where does the process sit while the computer is in sleep mode, and how is it accessed?

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When you set which devices are allowed to wake the computer from sleep, the computer instructs the hardware what to allow to apply power to the computer. The OS programs the hardware to respond appropriately, it doesn't make the decision at wake time because it would have to already be awake to do that.

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Ok. But how does the hardware know that something is being pressed and which piece of hardware is ok to respond to and which isn't? Is that information stored similar to the way the BIOS is? – Cygnus X Jan 5 '13 at 19:02
It is stored in configuration registers in the various pieces of hardware. – David Schwartz Jan 5 '13 at 20:24

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