By Richard Heller
Up until a few years ago there were only three common methods to connect devices such as printers and scanners to your computer, the printer port, the serial port and a SCSI interface. With the release of Windows 98, there are now at least four ways of connecting devices, with one or two others just making their appearance.
With the introduction of the Universal Serial Bus or USB, you can now connect anything from mice and keyboards to scanners and modems. One of the real advances in this technology is that you can plugin or unplug these devices without turning the computer off. This ability is known as hot swap, and it means that you no longer have to restart your computer when you want to connect your digital camera to the computer.
The USB device standard is designed to allow you to connect up to 128 devices to a single connection. With most computers only having two USB ports, how is this accomplished?
The answer is simple; you connect a box, called a hub, to one of the existing ports. The hub is like an extension cord; it adds four USB ports to the computer. The nice thing is that the hubs can be connected together, allowing four more ports for each hub connected. But with the hot swap ability of USB, you would only need enough ports to handle the devices that you want connected all the time such as your mouse, keyboard and scanner. With a four-port hub, you would still have one connection free to handle your camera, MP3 player or other device that you didnt use all the time.
If your computer doesnt have USB ports, they can be added easily. A plug-in card that contains two ports sells for about $30. In order to use the card your computer has to be a Pentium processor or better, and you have to be running Windows 98. Some of the later versions of Windows 95 offered support for USB, but most USB devices do not work with that configuration.
Probably the nicest thing about the USB standard is that all devices connected to the bus use the same interrupt or IRQ. Your computer only has 16 IRQs that are used by the hard drive controller, the sound card, the modem; in fact, all the hardware in your computer shares these IRQs. You can run into problems when devices such as modems and mice try to use one IRQ. As you move the mouse, a signal is generated that causes noise in your modem connection. It is very difficult to make changes in the hardware and software to correct these conflicts.
With USB, the driver software handles these conflicts and allows these devices to be connected and work together. Because it is a relatively high-speed connection, it can temporarily put a device on hold while getting the data from another device. With USB, you can add literally hundreds of cool things to your computer just by plugging in a cable.
Richard Heller is an independent computer specialist who specializes in repairs, installation, upgrades, technical support, Internet sharing, data recovery and diagnostics. If you have any computer or service-related questions, please send them to The Rock River Times or e-mail firstname.lastname@example.org.