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    How does power-up timer work?

    Discussion in 'Apple and Mac OS X' started by taelrak, Sep 5, 2007.

  1. taelrak

    taelrak Lost

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    So alarm clocks have this feature where they power up your computer after shut down at a specific time (provided you don't have passwords in place).

    So my question is, since the computer's off (not just sleeping, but completely off), how does it know when to turn itself on?
     
    taelrak, Sep 5, 2007
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  2. Kwakkel

    Kwakkel Weirdo

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    There's a BIOS feature that does the same. Maybe they activate that one?
     
    Kwakkel, Sep 5, 2007
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  3. system_159

    system_159 Notebook Deity

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    Indeed, the time of the wake up is stored into non-volatile BIOS(or in our case, EFI) memory. This is what people call CMOS, or EEPROM, or embedded flash memory. It's able to keep it's memory active due to a small battery that has no other function(CMOS battery).
    Seeing as how the CMOS has a real time clock built in, it's not hard to figure out the rest :)
     
    system_159, Sep 5, 2007
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  4. Geek94

    Geek94 Notebook Consultant

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    I have never seen a program in Windows able to modify BIOS settings in Windows. Is this a feature of EFI?
     
    Geek94, Sep 5, 2007
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