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In USB 3.0, dual-bus architecture is used to allow both USB 2.0 (Full Speed, Low Speed, or High Speed) and USB 3.0 (SuperSpeed) operations to take place simultaneously, thus providing backward compatibility. The structural topology is the same, consisting of a tiered star topology with a root hub at level 0 and hubs at lower levels to provide ...
Full speed (FS) rate of 12 Mbit/s is the basic USB signaling rate defined by USB 1.0. All USB hubs can operate at this rate. High speed (HS) rate of 480 Mbit/s was introduced in 2001 by USB 2.0. High-speed devices must also be capable of falling-back to full-speed as well, making high-speed devices backward compatible with USB 1.1 hosts ...
The Hi-Speed USB logo. USB 2.0 was released in April 2000, adding a higher maximum signaling rate of 480 Mbit/s (maximum theoretical data throughput 53 MByte/s [25]) named High Speed or High Bandwidth, in addition to the USB 1.x Full Speed signaling rate of 12 Mbit/s (maximum theoretical data throughput 1.2 MByte/s). [26]
The physical phenomena on which the device relies (such as spinning platters in a hard drive) will also impose limits; for instance, no spinning platter shipping in 2009 saturates SATA revision 2.0 (3 Gbit/s), so moving from this 3 Gbit/s interface to USB 3.0 at 4.8 Gbit/s for one spinning drive will result in no increase in realized transfer rate.
There are five speeds for USB data transfer: Low Speed, Full Speed, High Speed (from version 2.0 of the specification), SuperSpeed (from version 3.0), and SuperSpeed+ (from version 3.1). The modes have differing hardware and cabling requirements.
USB 3.0 SuperSpeed and USB 2.0 High-Speed versions defined USB 3.0 SuperSpeed – host controller (xHCI) hardware support, no software overhead for out-of-order commands; USB 2.0 High-speed – enables command queuing in USB 2.0 drives; Streams were added to the USB 3.0 SuperSpeed protocol for supporting UAS out-of-order completions
Specified USB data rates of 1.5 Mbit/s (Low-speed), 12 Mbit/s (Full-speed), 480 Mbit/s (High-speed) and 5 Gbit/s (SuperSpeed). xHCI 1.0, errata files 1-4: Released on January 17, 2011. Incorporated initial review feedback from larger 1.0 public audience, Save-Restore clarifications, and Hardware LPM support.
USB 3.0 was slow to appear in laptops. Through 2010, the majority of laptop models still contained only USB 2.0. ... the USB version used, the speed in which the USB ...