Short for Universal Serial Bus, an external bus standard that supports data transfer rates of 12 Mbps. A single USB port can be used to connect up to 127 peripheral devices, such as mice, modems, and keyboards. USB also supports Plug-and-Play installation and hot plugging. Starting in 1996, a few computer manufacturers started including USB support in their new machines. It wasn't until the release of the best-selling iMac in 1998 that USB became widespread. It is expected to completely replace serial and parallel ports.
this USB cable (square B end) sends data and power to a device
USB 1.1 is the standard that developed in regards to the 1996
device. One of the great things about USB is that the connections allows
the transfer of data and also provides power.
USB 2.0 (Hi-Speed USB), is an external bus that supports
data rates up to 480Mbps. USB 2.0 is an extension of USB 1.1. USB 2.0
is fully compatible with USB 1.1 and uses the same cables and connectors.
Hewlett-Packard, Intel, Lucent, Microsoft, NEC and Philips jointly led
the initiative to develop a higher data transfer rate than the 1.1 specification
to meet the bandwidth demands of developing technologies. The USB 2.0
specification was released in April 2000.
If you mix USB 1.1 and USB 2.0 (devices, ports, hubs, cables, etc) the system will work at the speed of the slowest component.
The USB symbol, is a marker for spotting the USB port. The port itself on the computer looks like these connectors.
You can get USB hub that will take one USB port and convert
it to a number of USB ports. Many will offer other port connectors as
well.
the USB 1.1 or 2.0 cable are identical
USB ports on the computer are usuall ganged together
the USB A rectangular end attaches to the computer
the USB B square end attaches to the device