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The functions needed to make a microprocessor into a computer reads like a laundry list for a three-ring circus—long and exotic, with a trace of the unexpected. A fully operational computer requires a clock or oscillator to generate the signals that lock the circuits together; a memory mastermind that ensures each byte goes to the proper place and stays there; a traffic cop for the expansion bus and other interconnecting circuitry to control the flow of data in and out of the chip and the rest of the system; office-assistant circuits for taking care of the daily routines and lifting the responsibility for minor chores from the microprocessor; and, in most modern computers, communications, video, and audio circuitry that let you and the computer deal with one another like rational beings.

Every computer manufactured since the first amphibians crawled from the primeval swamp has required these functions, although in the earliest computers they did not take the form of a chipset. The micro-miniaturization technology was nascent, and the need for combining so many functions in so small a package was negligible. Instead, computer engineers built the required functions from a variety of discrete circuits—small, general-purpose integrated circuits such as logic gates—and a few functional blocks, which are larger integrated circuits designed to a particular purpose but not necessarily one that had anything to do with computers. These garden-variety circuits, together termed support chips, were combined to build all the necessary computer functions into the first computer. The modern chipset not only combines these support functions onto a single silicon slice but also adds features beyond the dreams of the first computer's designers—things such as USB ports, surround-sound systems, and power-management circuits. This all-in-one design makes for simpler and far cheaper computers.

Trivial as it seems, encapsulating a piece of silicon in an epoxy plastic package is one of the more expensive parts of making chips. For chipmakers, it's much more expensive than adding more functions to the silicon itself. The more functions the chipmaker puts on a single chip, the less each function costs. Those savings dribble down to computer-makers and, eventually, you. Moreover, designing a computer motherboard with discrete support circuitry was a true engineering challenge because it required a deep understanding of the electronic function of all the elements of a computer. Using a chipset, a computer engineer need only be concerned with the signals going in and out of a few components. The chipset might be a magical black box for all the designer cares. In fact, in many cases the only skill required to design a computer from a chipset is the ability to navigate from a roadmap. Most chipset manufacturers provide circuit designs for motherboards to aid in the evaluation of their products. Many motherboard manufacturers (all too many, perhaps) simply take the chipset-maker's evaluation design and turn it into a commercial product.

You can trace the chipset genealogy all the way back to the first computer. This heritage results from the simple need for compatibility. Today's computers mimic the function of the earliest computers—and IBM's original Personal Computer of 1981 in particular—so that they can all run the same software. Although seemingly anachronistic in an age when those who can remember the first computer also harbor memories of Desotos and dinosaurs, even the most current chipsets must precisely mimic the actions of early computers so that the oldest software will still operate properly in new computers—provided, of course, all the other required support is also present. After all, some Neanderthal will set switchboards glowing from I-95 to the Silicon Valley with threats of lawsuits and aspersions about the parenthood of chipset designers when the DOS utilities he downloaded in 1982 won't run on his new Pentium 4.

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