Chapter 9. Expansion Buses

Given an old house, closets packed tighter than the economy section of a Boeing 737, and a charge card, most people will broach the idea of adding to their homes . After all, when you need more room, nothing seems more natural than building an addition. If you have more ambition than second thoughts, the most humble bungalow can become a manse of overwhelming grandeur with a mortgage to match.

Making the same magic on your computer might not seem as natural, but it is. Adding to your computer is easier than adding to your house ”and less likely to lead to bankruptcy and divorce ”because, unlike a house, computers are designed to be added to. They sprout connectors and ports like a Chia pet does hair.

Computers are different, however, in that the best way to add to them is not on the outside. Odd as it may seem, you can effectively increase the power and capabilities of most computers by expanding them on the inside.

The design feature key to this interior growth is the expansion bus . By plugging a card into your computer's expansion bus, you can make the machine into almost anything you want it to be ”within reason, of course. You can't expect to turn your computer into a flying boat, but a video production system, international communications center, cryptographic analyzer, and medical instrument interface are all easily within the power of your expansion bus. Even if your aim is more modest, you'll need to become familiar with this bus. All the most common options for customizing your computer ”modems, network interface cards, and television tuners ”plug into it. Even if your computer has a modem, sound, and video built in to its motherboard, forever fixed and irremovable, these features invisibly connect to the computer's expansion bus.

The expansion bus is your computer's electrical umbilical cord, a direct connection with the computer's logical circulatory system that enables whatever expansion brainchild you have to link to your system. The purpose of the expansion bus is straightforward: It enables you to plug things into the machine and, hopefully, enhance the computer's operation.