Hack #82. Get the Most out of USB

Use separate USB ports to get the best performance out of your high-speed devices.

The USB port in your PC is designed to supply up to 12 (USB 1.1) or 480 (USB 2.0) megabits per second throughput to attached devices, but that is total throughput and must be shared with all connected devices. If you use two USB ports on your PC at the same time, it's best to have two USB controllers, each delivering the total throughput. Although this limitation is more noticeable with the slow USB 1.1 speeds, you'll certainly notice it if you do something I/O-intensive with USB 2.0, such as copying large files between two USB mass storage devices.

To check if you have two USB controllers, open Windows Device Manager and expand the Universal Serial Bus controllers branch in the list. If you have two separate controllers, they will be listed, as shown in Figure 8-6.

Device Manager lists two USB controllers

Figure 8-6. Device Manager lists two USB controllers

If you need to connect and use two high-speed USB devices at the same time, such as a scanner, external disk drive, video camera, or network adapter, connect them to different ports on your PC so neither one suffers from sharing bandwidth. If you need to support more than two high-speed devices operating at the same time, you will have to add a USB hub or install additional USB controllers, either with an add-in PCI card for your desktop or a PC card for ...

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