Solved query power supply versus os logic

Toshiba Satellite c655-s5082 laptop
August 1, 2012 at 11:07:24
Specs: Vista, Any
If I hold down the power button on a Vista OS laptop I know that the OS Logic will check the registry settings to see what action to take, such as shut down, sleep, etc. But if the action is set to 'do nothing' then the OS just continues to run, however at some point, seconds later the power is then cut and the laptop dies. Therefore what process controls this point once the OS has ignored the interrupt. Does control go back to the power button circuitry/motherboard or is it a simple mechanical switch that cuts the power after the button has been held for so long, or something else?

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August 1, 2012 at 12:16:20
I believe it is mechanical. I am not sure if this is true anymore but when I first started working with computers I was told "You can override anything with the power button" in other words if you hold it in long enough the machine will shut off. Don't take any of this is gospel as I am no highly trained technician nor do I really no much about laptops. I believe the "Do nothing" setting refers to if the button is pushed and released not if it is held in for six to eleven seconds.


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August 1, 2012 at 13:02:30
✔ Best Answer
All PCs, Laptops and Desktop will shut down if the power button is held for four seconds. This is under the control of the BIOS and is not a controlled shut down, it just removes the power to the motherboard in case the of a total sieze up so that Ctrl-ALt-Delete doesnt work, which is also under the control of the BIOS.

It reverses the process that started the computer running in the first place in that out the power supply into standby mode and there it stay until the power button is pressed again. This is all done under software control.

The "Do Nothing" only refer to the a momentary pressing of the button and if set to shut down, will do a controlled shut down that same as clicking shut down from the start menu.


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August 1, 2012 at 21:30:12
Many thanks for both replies. If the BIOS takes control as I suspected it did as it has to be a form of reverse POST can I find this documented in literature anywhere?

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