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Permalink Reply by ANJU on May 17, 2013 at 5:14

Mr. Singh,

Universal Serial Bus (USB) is an industry standard developed in the mid-1990s that defines the cables, connectors and communications protocols used in a bus for connection, communication and power supply between computers and electronic devices. Now even devices like smart phones, PDAs and video game consoles are connected to the computers with USB ports allowing recharging and communication thereby replacing the requirement of adapters and power chargers.

USB3.0 was released in November 2008, almost eight years after the release of USB 2.0. USB 2.0 offers transfer rates of 480 Mbps and USB 3.0 offers transfer rates of 4.8 Gbps - that's 10 times faster. USB 3.0, the latest version of USB (Universal Serial Bus), provides better speed and more efficient power management than USB 2.0. USB 3.0 is backward compatible with USB 2.0 devices; however, data transfer speeds are limited to USB 2.0 levels when these devices inter-operate. USB 3.0 Connectors are different from USB 2.0 Connectors and the 3.0 connectors are usually colored blue on the inside in order to distinguish them from the 2.0 connectors. USB 3.0 is compatible with USB 2.0. However, the USB 3.0 product will perform at the same level as a USB 2.0 product, so speed and power benefits will not be fully realized.

I hope the above information is satisfactory.

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Permalink Reply by DR MD GULNAWAZ AZAM on May 17, 2013 at 8:07

USB(Universal Serial Bus) is the most popular connecting device that used to connect a computer to  external devices such as  digital cameras, printer, scanner, external hard disk and others  external backup devices. In modern day’s computer, numbers of USB port are available for connecting such devices. USB is a cross-platform technology that is supported by most of the major operating system.  USB is based on hot-swapped technology that means , the USB devices can be added and removed without having to restart the computer  and it is also worked in “plug and play” concept that is when we can insert USB based devices in our computer through USB port , our computer  detect the devices automatically  for connecting and installing. 

The version of USB is basically the determination of data transfer rate between computer and USB devices.  There are three versions of USB:

(1)    USB 1.0

USB 1.0 is the  original version of USB,  it’s provides support of  two interface speeds: Low speed at 1.5 MB/s and full speed at 12 MB/s. Low speed devices are typically interactive input devices such as Keyboards , Mice  or games controllers. Full speed devices are typically application specific input devices such as Microphones, Cameras and Printers.  But modern day’s computer technologies, all USB based devices are upgrade into USB 2.0

(2)    USB 2.0:  

The USB 2.0 standard was developed to offer a complimentary high-speed data transfer rate.  Due to integration of different types of external devices, the Universal Serial Bus is the most widely deployed computer peripherals interface in history, enabling simple plug and play connectivity for a wide variety of devices to enhance the computer experience. As PC’s and peripheral devices have added more processing bandwidth, performance and features,   USB 2.0 offers high-speed transfer rate at 480 MB/s.

(3)    USB 3.0     

USB 3.0 is a major advancement over USB 2.0, far greater in impact than what USB 2 was over USB 1.0. The biggest difference is the speed at which it can communicate with the computer's host controller and the biggest advantage is that it can maintain a backwards compatibility with USB 1.0 and 2.0. USB 2 had a maximum speed of 480 MB/s, which was great at that time but now it might not be enough because we now have USB thumb drives that are 64 GB in size, cell phone and PDAs that have a lot of internal storage built in, and even at 480 MB/s a full transfer of data in between devices can take a long time. In comparison to this, USB 3.0 boasts a maximum transfer speed of 4.8 GB/s which is almost 10 times faster than USB 2.0.  USB 3.0 brings significant performance enhancements to the ubiquitous USB standard, while remaining compatible with the billions of USB enables devices currently deployed in the market.  USB 3.0 will deliver    approx 5 GB/s data transfer rate. It is support Sync-N- Go technology that minimizes user wait time and provides Optimized Power Efficiency.   

The physical difference between USB 2.0 and USB 3.0 is the number of wire connections. This new topology greatly improves bus utilization resulting in improved system throughput. USB 2.0 uses four wires which supports half-duplex communication. In this architecture, a single bi-directional data pipe is used where data only flows in one  direction at any given time. In comparison, USB 3.0 add five wires for a total of nine wires and utilizes a unicast dual-simplex data interface that allows for two uni-directional  data pipes, with each pipe handling communication for a single direction.

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