How do electronics turn back on when you “restart”? Wouldnt it still be on in some capacity to do that when it’s off?

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How do electronics turn back on when you “restart”? Wouldnt it still be on in some capacity to do that when it’s off?

In: Technology
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There is battery that powers the CMOS (Complementary metal-oxide-semiconductor), which holds a little bit of memory on a computer motherboard that stores the Basic Input/Output System (BIOS) settings, which allows the computer to boot up.

In those cases, the device usually never actually turns itself off during a restart. There’s a couple of ways this could go.

A lot of devices have many small computers inside of them that work in tandem with the larger computer that does the work. Part of a PC is a system that handles “power management”, usually it’s part of the motherboard. When it’s told to restart, it goes through all the motions of shutting the computer down, but stops short of breaking the supply of power to the main components. Instead, once it’s satisfied everything is in a safe, “shut down” state, it pokes the part of the motherboard responsible for bootup and says, “Hey, you just got powered on, wake everyone else up!” That part of the system has no clue it’s only been powered down for a few moments, so it goes about its business.

Non-PC devices do it the same way: they have some system responsible for power management. It’s the first thing to “wake up” when you turn the device on. So in this case, it doesn’t turn itself off. It turns everything else off, then turns everything else back on.

So you’re probably asking, “But if we have to restart because things are glitchy, what happens if power management gets glitchy?” First, that’s really rare. Power management systems are pretty simple systems, so they’re less likely to have weird bugs. Second, when it happens, the device obviously takes too long to restart, so eventually you unplug it and plug it back in. That restarts the power management system, too.