Speed
To allow high-speed (USB 2.0) devices to operate in their fastest mode all hubs between the devices and the computer must be high speed. High-speed devices should fall back to full-speed (USB 1.1) when plugged in to a full-speed hub (or connected to an older full-speed computer port). While high-speed hubs can communicate at all device speeds, low and full-speed traffic is combined and segregated from high-speed traffic through a transaction translator. Each transaction translator segregates lower speed traffic into its own pool, essentially creating a virtual full-speed bus. Some designs use a single transaction translator, while other designs have multiple translators. Having multiple translators is a significant benefit when one connects multiple high-bandwidth full-speed devices.
It is an important consideration that in common language (and often product marketing) USB 2.0 is used as synonymous with high-speed. However, because the USB 2.0 specification, which introduced high-speed, incorporates the USB 1.1 specification such that a USB 2.0 device is not required to operate at high speed, any compliant full-speed or low-speed device may still be labelled as a USB 2.0 device. Thus, not all USB 2.0 hubs operate at high-speed.
Read more about this topic: USB Hub
Famous quotes containing the word speed:
“Among the laws controlling human societies there is one more precise and clearer, it seems to me, than all the others. If men are to remain civilized or to become civilized, the art of association must develop and improve among them at the same speed as equality of conditions spreads.”
—Alexis de Tocqueville (1805–1859)
“Life is too short to waste
In critic peep or cynic bark,
Quarrel or reprimand:
‘Twill soon be dark;
Up, heed thine own aim, and
God speed the mark!”
—Ralph Waldo Emerson (1803–1882)
“It was undoubtedly the feeling of exile—that sensation of a void within which never left us, that irrational longing to hark back to the past or else to speed up the march of time, and those keen shafts of memory that stung like fire.”
—Albert Camus (1913–1960)