Appendix A: USB 2.0 specification primer
USB terminology 15
USB topology 17
ConnectingUSB devices 18
PoweringUSB devices 18
USB connectors andcables 19
USB connectors 19
USB cables 20
Prohibitedcable assemblies 20
USB cable length 21
ExtendingUSB connections 21
Basic USB connection 21
Compounddevice connection 22
Host with internal non-roothuband compounddevice c onnection 22
Youcan use this section as a referenceto c ommonUniversal Serial Bus (USB) 2.0 terms, rules and
conventions.

USB terminology

Thesedefinitions are derivedfrom the Universal Serial Bus Specification, revision 2.0, and are used
int his document.
Term Definition
Active (device) A device (hubor extension cable) with circuitry for regeneratingthe USB
signals. Formore information, see PoweringUSB devices on page18.
Device A logical orphysical entity that performs a function. Theact ualentity
describeddependson the context of the reference. At the lowest level,
devicemay refert o a singlehardware component,as in a memory device.
At a higherlevel, it may refer to a collection of hardwarecomponentst hat
performa particularfunction, s uchas a USB interface device. When used
ina non-specific reference, a USB device is either a hub ora f unction.

Appendix A

15