Appendix BGlossary of USB Terms


Handshake packet indicating a positive acknowledgement between devices, or a host and device on the Universal Serial Bus.

Active Device:

A device that is not in the suspended state and is powered on.

Asynchronous Data:

Data that is sent across the Universal Serial Bus without regard to timing requirements; the opposite of isochronous.


Persistent data on the bus that is not expected by any device or the host.


The amount of data that can be transmitted over the bus in a given amount of time; this is usually expressed in bits per second (bps).


A single element of data within the computer (or on the bus) that is either a 1 or a 0 (indicating high voltage or low). There are ...

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