USB 3.0 is capable of supporting data transfer rates of up to 5 gigabits per second (Gbps), which is 10 times faster than the previous high-speed USB 2.0 transfer speeds. With its higher speeds and enhanced power efficiency, external hard disk drives are the first SuperSpeed USB 3.0 devices to appear on the market.
As the first step toward WD’s and NEC Electronics’ goal to promote the SuperSpeed USB 3.0 standard, the companies plan to develop a USB Attached SCSI Protocol (UASP) driver to deliver hard drives with very high performance, mass-storage capacity. UASP is a new industry-standard, high-performance mass-storage protocol being developed for SuperSpeed USB 3.0 to overcome the performance boundaries of the Bulk Only Transfer (BOT) protocol, which has been used for traditional USB 2.0 speeds. The new UASP driver will be used with NEC Electronics’ USB 3.0 xHCI (eXtensible Host Controller Interface) host controller (part number µPD720200), which appeared on the market as the world’s first USB 3.0 host controller in June 2009.