system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How are game consoles and other computer devices able to turn themselves off and on again after an update?
gpt
Well, technically the device is never really powered off. The CPU and the power supply are linked by some input/output lines and so there's some limited control the CPU (via the motherboard) has over the power supply like "go into low power mode" or "go to standby".... which just keeps the CPU running at slow speed and contents of memory in the RAM and so on. 

But in the case of a reboot for say a Windows update. 

- computer operating system downloads the update. 
- inserts commands into its startup scripts to run the new code instead of the old
- sets a flag at the end of the startup scripts that if it gets to this point it must have worked ok. Otherwise roll back the changes after another reboot. 
- tells self to reboot
- CPU pretends like its shutting down, powering off and on again
- follows its startup scripts
- it worked, removes that flag/check 

Literally there are commands like "reboot" or "shutdown -R 'now'" to shutdown or reboot the operating system. These in turn end with commands for the CPU to literally turn itself off and on again.