The difference between a computer and a television set at first seems obvious—one has a keyboard and the other doesn't. Take a look at the modern remote control, however, and you'll see the difference is more subtle. It's something that's going on behind the screens. When you sit around watching the television, you're gradually putting down roots as a couch potato or some less respected vegetable, but when you sit at the computer, it watches you. It wants to know what you want. It listens to your thoughts, relayed through the keyboard, to carry out your commands—calculating, organizing, alphabetizing, filing away, drawing, and editing. No other machine takes information from you and handles it so adroitly. That's the computer's power as a data-processing machine, a thinking machine.
As a physical entity, the processing part of a desktop computer is inside the big box you may call the system unit, CPU (for central processing unit), or simply "the computer." But the processing part of the computer only takes up a fraction of the space occupied by the system unit. All the essential processing power of the computer fits into a handful of circuit components—the microprocessor, the chipset, and the BIOS. Each has its own function in bringing the processing power of the computer to life, and each is substantially different in concept, design, and operation.
The microprocessor, the chipset, and the BIOS—and the rest of the computer as well—are themselves built the same. Each is a tiny slice of nearly pure silicon that has been carefully fabricated into a digital electronic circuit. Because all three processing components of a computer have this same silicon/electrical foundation—indeed, all of today's electronic devices share these same design elements—we'll talk about the underlying technologies that make the processing of a computer possible before looking at the individual components themselves.