Appendix A: USB 2.0 specification primer
USB terminology 15
USB topology 17
Connecting USB devices 18
Powering USB devices 18
USB connectors and cables 19
USB connectors 19
USB cables 20
Prohibited cable assemblies 20
USB cable length 21
Extending USB connections 21
Basic USB connection 21
Compound device connection 22
Host with internal non-root hub and compound device connection 22
You can use this section as a reference to common Universal Serial Bus (USB) 2.0 terms, rules and
conventions.
USB terminology
These definitions are derived from the Universal Serial Bus Specification, revision 2.0, and are used
in this document.
Term Definition
Active (device) A device (hub or extension cable) with circuitry for regenerating the USB
signals. For more information, see Powering USB devices on page 18.
Device A logical or physical entity that performs a function. The actual entity
described depends on the context of the reference. At the lowest level,
device may refer to a single hardware component, as in a memory device.
At a higher level, it may refer to a collection of hardware components that
perform a particular function, such as a USB interface device. When used
in a non-specific reference, a USB device is either a hub or a function.
Appendix A
15
