The Operating System

Every personal computer ever made has an operating system at its heart. An operating system (often abbreviated as OS) is a highly specialized program that tells the computer's hardware components how to behave and talk to each other. It also takes care of the user interface—the part of the software that handles interaction with a computer's users. This latter part of the system software gets all of the attention, mostly because it's the most visible part of the operating system. Operating systems go much deeper than their user interfaces, though.

Under your Mac's serene surface area of windows and icons is a labyrinth of programming code that's busily moving data between the hard drive, the memory, and the monitor, all the ...

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