dacs.doc electric

UNIVERSAL SERIAL BUS (USB) is an interface for connecting peripherals such as printers and scanners to PCs. It will probably replace serial and parallel ports as the primary means for connection of peripherals. USB transfers data at about 12MB per second, which is considerably faster than the data transfer rate of serial ports (115 kilobits/second) or most parallel ports (50 to 100 kilobytes/second), although EPP (Enhanced Parallel Ports) can run at 500 kilobytes to 2 megabytes per second. This makes the USB port ideal for several types of slow and medium-speed peripherals, such as mice, keyboards, digital cameras, game input devices, scanners, printers, and modems. You probably won’t find USB versions of hard drives, because even USB can’t transfer data fast enough to meet the needs of these devices.

USB is more than just improved speed. Setting up a USB peripheral involves simply plugging it into the USB port and letting the computer “feel” that it’s there. Once your computer searches for new hardware and detects the device, the computer automatically loads the software needed to operate the device. You may have to load some additional software for extra programs that the peripheral manufacturer throws in, but you shouldn’t have to install anything to get the peripheral to work.

You can connect up to 127 peripherals to your computer through the two USB ports found on most current PCs. You connect multiple peripherals to your computer in a formation known as a daisy-chain. Many USB peripherals have a USB slot into which you can plug another USB peripheral. You plug your first USB peripheral into the computer, then plug the second peripheral into the first peripheral, then the third into the second, and so on. You can also use USB hubs to connect several devices.

And don’t forget hot swapping! Hot swapping lets you add or remove a peripheral without shutting down and restarting your system. If you’re at your office and someone wants to borrow your USB digital camera, you can simply unplug it from your computer and plug it into the other person’s computer. The digital camera is ready to go without configuration hassles and without shutting down either computer.

If you don’t already have a USB port on your PC, you can buy one in the form of a USB expansion card. The PCI-to-USB upgrade kits cost about $50. Your PC should be running Windows 98 for best results. The latest version of Windows 95 can use USB, but it often does so with mixed results. Win98 has the best USB support, and Windows NT 4.0 users are out of luck. That version does not support USB.

So does this mean that serial and parallel ports are a thing of the past? Not yet. Serial and parallel ports are still found on computers made today. Part of the reason is because many computer users still have several non-USB peripherals, and aren’t ready to trade them in. But if given the choice in a new device, give USB some serious consideration.