USB (Universal Serial Bus) - Nanocdac

USB is a standard for a wired connection between two electronic devices, including a mobile phone and a desktop computer. The connection is made by a cable that has a connector at either end. One end, the one that plugs into the computer, is the same across all USB cables while the one that plugs into the mobile device can be of various types such as mini USB, micro USB or a proprietary connector.

Multiple versions of USB have been developed by the computer industry:

• USB 1.0 and 1.1: the first commercial versions supported a maximum data rate of 12 Mbps
• USB 2.0: the current version supports a much faster theoretical maximum rate of 480 Mbps
• USB 3.0: the future standard is expected to support up to 4.8 Gbps

In addition to their data transferring application, USB cables also carry an electric charge that can be used to power peripherals (such as USB mice or keyboards), and many mobile phones can be charged through their USB port.

Using USB for Local Networking

To build a USB network, simply connect USB cables to the USB ports on those devices. USB is plug and play compatible, meaning the operating system USB driver software automatically detects and configures device connections. One USB network supports up to 127 devices.

USB interfaces are backward compatible; for example, a USB 2.0 and a USB 1.1 can be networked. When two ends of a connection support different versions of USB, the link automatically runs at the lower speed of the older version.

USB Hubs:

Almost all computers sold today have USB ports, and most of them support USB 2.0. The number of ports they have is usually limited, though. Between two and six ports are common. USB allows connecting USB hubs to add more USB ports.

The hubs themselves are also USB 1.1 or USB 2.0 compliant. On an USB 2.0 controller, standards can be mixed. Devices connected to a USB 1.1 hub will only go as fast as USB 1.1 rates.

Figure: USB Hub

Advantages:

• Much more resistant to scratches unlike CD ROMs and floppies
• Much more convenient, will work with almost any computer as long as there is a flash drive
• Great storage space
• It's small size is convenient for carrying, and takes little space
• One can purchase a USB that more reflects them through its colors and design

Disadvantages:

• It's small size also means it can be lost easily and/or forgotten
• Its life span can be short, about several hundred thousand cycles
• As the device ages the speed of writing process gradually slows
• Only a few USB flash drives are equipped with a write-protect mechanism, meaning those that don't have the protection could be contaminated by whatever virus the computer it was connected to has
• If inappropriately removed from the USB drive without being ejected, it become damaged or loses the data saved to it.

for more info   http://www.nanocdac.com/