A single system can have multiple hard drives. One of those will be the bootable system drive.
Where are the various sorts of data stored? Videos and images might be relegated to a massive secondary drive/disk, whereas system and other user data may be housed on the primary/system drive.
A single system can have multiple hard drives. One of those will be the bootable system drive.
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In a laptop, as well? (serious question - I never owned one, only a desktop).