Chapter 11. Ports

No computer has everything you need built in to it. The computer gains its power from what you connect to it—its peripherals. Somehow your computer must be able to send data to its peripherals. It needs to connect, and it makes its connections through its ports.

Today's computers include two or three of these modern interfaces. Those that you're likely to encounter include Universal Serial Bus (USB), today's general-purpose choice; FireWire, most popular as a digital video interface; IrDA, a wireless connection most often used for beaming data between handheld computers; Bluetooth, a radio-based networking system most suited for voice equipment; legacy serial ports, used by a variety of slower devices such as external modems, drawing tablets, and even PC-to-PC connections; and legacy parallel ports, most often used by printers. Table 11.1 compares these port alternatives.

Table 11.1. A Comparison of Serial Interfaces

Standard	Data Rate (Current)	Medium	Devices per Port
ACCESS.bus	100Kbps	Four-wire shielded cable	125
Bluetooth	723Kbps	Radio	8
FireWire (IEEE-1394)	400Mbps	Special six-wire cable	63
IrDA	4Mbps	Optical	126
Parallel (IEEE-1284)	2Mbps	25-conductor cable	1
Serial (RS-232C)	115,200bps	Twisted-pair	1
USB	480Mbps	Special four-wire cable	127

If you were only to buy new peripherals to plug into your computer, you could get along with only USB ports. Designed to be hassle-free for installing new gear, USB is fast enough (at least in its current version 2.0) that you need not consider any other connection. You can consider all the other ports special-purpose designs—the legacy pair (parallel and serial) for accommodating stuff that would otherwise be gathering dust in your attic; FireWire for plugging in your digital camcorder; IrDA for talking to your notebook computer; and Bluetooth for, well, you'll think of something.