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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 ...
USB 2.0 provides for a maximum cable length of 5 metres (16 ft 5 in) for devices running at high speed (480 Mbit/s). The primary reason for this limit is the maximum allowed round-trip delay of about 1.5 μs. If USB host commands are unanswered by the USB device within the allowed time, the host considers the command lost.
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]
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 ...
A specific maximum speed is also not mentioned, but the other requirements for TB4 all refer to DP 1.4 and its maximum speed of HBR3. [48] TB5 renews the same guarantee [ 49 ] for "80 Gbps" cables while referencing the DP 2.1 specification (up to UHBR20 speeds).
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.
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.