USB, or Universal Serial Bus, is a hardware bus standard that allows users to plug a peripheral device into a USB port and have it automatically configured and ready to use. It is one of the success stories of the personal computer. It not only works well, but also makes the life of the average computer user easier.

Most computers that were manufactured after 1995 have USB ports. Windows 95 had only erratic support for USB, but all newer Windows operating systems have support for USB. iMacs and other Apple computers also support USB.

So what's the big deal about USB? USB has a lot going for it. It has three great features: speed, power, and ease of use.

What's a Port?

A port is an interface for attaching external devices to a computer. The original IBM personal computers came with two ports -- a serial port and a parallel port. Typically, devices such as modems were attached to the serial port and devices such as printers connected to the parallel port. Another type of port called the SCSI port became a mainstay in the Mac world but never caught on in a big way in the PC world.

Ports not only connects an external device, but it also controls the transfer rate, the rate at which data can be transferred between the computer and the attached device. This is where the USB port excels. On the average, USB allows data to travel ten times the speed of the normal parallel port. It is also faster than a serial port. This means that a USB printer or scanner can operate faster than a printer or scanner that hooks up to the parallel port. The average serial port transfer rate is 150 kbps; the parallel port is 1.2 mbps. The USB port transfers data is up to 12 mbps depending on the type of device that is connected.

Each of these different types of ports is uniquely different. While a computer can have several different types of ports built into it, each port can connect only its own distinctive type of peripheral. If a device is made with a parallel port connection, it can be hooked up only to a parallel port. If a device is made with a USB connection, it can be hooked up only to a USB port. Some printers come with dual support; they can be hooked up to either the parallel port or the USB port.

What Does USB Look Like?

To find the USB port on your computer, look at the back or side of your computer. Most of the ports have rows of small pins or pinholes where new peripherals can be plugged in. The USB port looks slightly different. It is a small thin opening about ½ " long. It has no obvious pins or pinholes. It is often, but not always, marked "USB.” Many computers have two USB ports.  Some even have the added convenience of USB ports in the front of the computer, a boon for devices like cameras, which are hooked up and removed often.

 USB 2

Why not take something good and make it even better? That’s just what the computer industry did with USB 2. With a maximum transfer rate of 480 mbps, or 60 mb per second, USB 2 is forty times faster than USB 1. Better yet, it is backwardly compatible with USB 1. That means that if your new computer comes with USB 2, you can still use your old USB devices. Of course, they will perform at USB 1 speeds, but they will still work properly. To take full advantage of the speed of USB 2, the devices that you purchase must be USB 2 enabled and must be run from a USB 2 port. These speedy devices have already made their appearance and are sure to be plentiful in the future. The speed of USB 2 will be beneficial to many devices including digital cameras, hard drives, and DVD drives. To recognize a USB 2 port or device, look for the USB High-Speed logo.

Although USB 2 support was not originally built into any of the current Windows operating systems, USB 2 will work with Windows 98 or better. If your new computer has USB 2 ports, Windows XP will have the necessary support. If you are adding a USB card to your current Windows XP computer, support is available through the Windows Update feature. In most cases, if you upgrade your computer with an add-on card, it will come with a USB 2 installation CD that will work with Windows 98 and Windows Me.

Stackable & Swappable

USB has other advantages as well. Although I can't imagine why anyone would want to, you can attach up to 127 devices to one USB port. USB ports are self-powered, so you can say goodbye to those big chunky power blocks. However, if you attach more than a few devices, you will need to add a self-powered hub, which is a small mechanism that provides extra power to the attached devices.

The idea behind USB is that the devices will be daisy-chained together. The USB device that you purchase should have another built-in USB port so you can hook other devices to it. Many of the USB monitors that I've seen come with three USB ports for attaching other devices. Some USB keyboards also have several built-in USB ports where you can hook up other devices. For instance, your mouse might connect to your keyboard, your keyboard to your monitor, and your monitor to your computer. This eliminates the mess of power cables that often accompany a computer system.

USB devices are hot swappable. You can plug in and remove any USB devices without turning the computer on and off. This is a great feature for those of us who want to purchase only one peripheral to use on two or more computers. It’s also great for devices like cameras that are attached and removed from the computer often.

USB Devices

Yu coan plug just about anything into a USB port: keyboards, cameras, mice, joy sticks, modems, zip drives, floppy drives, printers, and scanners. You can even purchase USB speakers to produce great digital sound on your computer. As you read this, more and more USB devices are becoming available. Eventually serial and parallel ports will disappear on new computers. So if you are adding a new device to your computer, you really should consider a USB device. By the way, USB devices do not cost any more than other peripherals.

Adding a  USBPort

If your computer doesn't have a USB port or you want to add the newer USB2 functionality, you can add USB or USB2 by buying an inexpensive adapter card that fits into a PCI slot in your computer.

If you have a notebook computer, you can purchase a USB port that fits into the card slot. However, you should be aware that USB devices can use a lot of your computer's power. This is not a problem if you have a desktop computer or are using your notebook computer with an A/C power cord. However, if you plan to run your portable computer on its batteries, a USB device can be a power drain on the batteries.