USB Connectivity

USB is a technology that allows computer users to connect up to 127 devices to their computer at the same time, such devices include USB scanners, USB keyboards, USB mice, USB digital cameras, USB-to-ethernet adapters, USB telephones, USB digital joysticks, USB CD-ROM drives, USB hubs, USB tape drives, USB floppy drives, and more.

How USB Works

One important thing to understand about USB connectivity is that it is a host-client system. In other words, your computer controls your USB devices through a tree-like directory similar to the one shown below. Note that USB cables always have the A-connector facing toward the host (your computer) and the B-connector facing toward the clients (USB devices). USB hubs will lie in between your computer and your devices with the type-B port on the upstream side and the type-A ports on the downstream side. (See diagram.)

Software and USB

Regarding software, USB requires Windows 95B (a version with USB support), Windows 98/98E, or Windows 2000. If a device requires additional software support, it will usually come with a "driver" (software on a floppy disk or CD-ROM). Macintosh computers that have USB ports on them support most USB devices.

USB Maximum Distance

Generally, the maximum distance between most USB devices and your computer is 5 meters (16 feet). However, slow USB devices, such as mice and keyboards, have a maximum distance of 3 meters (9.5 feet). One way to extend this distance is to use USB hubs (which repeat a signal). You can go an additional 5 meters if you put a hub between your computer and your USB device(s). You can do this up to 5 times for a maximum distance to 30 meters. Slow USB devices will only reach up to a total of 27 meters, depending on the length of your device that will plug into the final USB hub. 

Adding USB To Your Computer

How can you add a USB port to my computer?  Two ways: One way is to put a PCI or ISA adapter card onto your motherboard PCI slot (shorter white slots) or ISA slot (longer black slots). These are circuit board cards that fit into a slot on your motherboard and provide USB ports on a bracket through the back of you computer. Another way to add USB slots is to connect a USB-to-motherboard internal cable adapter. HOWEVER, your motherboard must be a USB supported motherboard, and you should check your motherboard manual for the standard 5-pin USB connector (5 pins in a row) of which you might have two sets of 5 pins. This is a bracket with USB ports on it that does not go into a PCI slot or ISA slot but instead has little cables with two 5-pin (10 pins total) connectors that plug into your motherboard. If your connection to your motherboard is different than this, you probably can only buy such a USB-to-motherboard adapter from the manufacturer of your motherboard (since it is not the standard USB connection).

USB Connectors

USB Direct Link Cable - This is a special cable that plugs into each computers' USB port. IMPORTANT: Do not plug a standard Type A-male to Type A-male USB cable! You must use a special USB Link cable with Type A male conectors. See our Connector Help section to see what USB connectors look like. Also, both computers must be running Windows with USB support (later versions of Windows 95 or Windows 98)

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Copyright © 2002 Øyvind Haugland
Sist endret:  13 januar 2019

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