USB 1.0 and USB 2.0 are serial bus standards that connect devices to computer systems. Most users probably know USB from devices like external hard drives, keyboards, mice but also mobile devices which are usually connected via USB to computer systems these days.
USB 2.0, also known as Hi-Speed USB, was the first upgrade to the USB standard in April 2000 which delivered faster transfer speeds. The maximum transfer speed increased from 12 Mbit/s for USB 1.0 devices to 480 Mbit/s for USB 2.0 devices, a huge jump that made the devices attractive for a number of applications, especially those involving the transfer of large files from or to the device.
If you transfer a large file from an USB device to a PC, you will surely appreciate the increase from the 1.5 Megabyte per second maximum transfer speed of USB 1.0 to the 60 Megabyte per second speed that USB 2.0 supports.
SuperSpeed USB, USB 3.0, which was demonstrated for the first time in 2007 will advance the serial bus standard once again. Transfer speeds have been raised to a speed of 5 Gbit/s which improves data transfer speeds tremendously.
To copy a 25 Gigabyte file devices connected through USB 1.0 need 9.03 hours, USB 2.0 devices need 13.09 minutes and USB 3.0 1.10 minutes under best conditions.
USB 3.0 receptacles are backwards compatible with USB 2.0 device plugs which basically means that computer users can still connect their USB 2.0 or USB 1.0 devices to a computer system supporting USB 3.0 ports only.
Transfer speed comparison (seconds)
|File size||USB 1.0||USB 2.0||USB 3.0|
Another interesting addition to USB 3.0 are power saving features which were especially designed for mobile devices. Packet traffic is no longer being broadcasted to the USB device which reduces its power usage. Additional power saving features like idle, sleep and suspend states have been added to USB 3.0 as well.
A device entering sleep mode will practically be left alone by USB 3.0 Hosts until itself initiates a device mode change. The power specs have been increased on the other hand to be able to provide devices (like external hard drives) with additional power for their operation.
First devices that make use of USB 3.0 are expected in 2009 but the main push towards USB 3.0 is expected to begin in 2010.
While faster transfer rates are without doubt the core improvement of USB 3.0, better power management needs to be mentioned as well. If your computer supports USB 3.0, it is highly recommended to buy devices that support it as well as you will speed up transfers significantly this way.
Update: USB 3.1, an update to the existing 3.0 standard was released in July 2013. This led to some confusion, as two standards, USB 3.1 Gen 1 and USB 3.1 Gen 2 are now available. USB 3.1 Gen 1 is basically the same as USB 3.0, while USB 3.1 Gen 2 doubles the speed of USB 3.0 to 10 Gbit/s.Advertisement
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