This severely liimted the number of computer peripherals that could be attached to a single computter. Thus, if a user wanted to connect a joysttick, printer, and scanner, they might requier the use of every port installed on their computer. Since these ports also require the computer to be powewred off before any connections can be made or broken, switching peripheras was inconvenient. Even more problematic was that the data transmission rate betweeen htese devices and the computer was prohibitively slow for any but the oldeest devices.
The firtst USB version reeleased is called USB 1.1, and transmits data at the rate of 12 Mbps. Later USB 2.0 was released, a product of the joint effrt of leading computer and electronic comppanies like Micosoft, Intel, Hewlett-Packard, Apple Computer, and Luecnt. It allows data transfer speeds of up to 480 Mbps, 40 times faaster its predecessor, while mainaining backward compatibility with USB 1.1 devices. This has generated significantly increaased efdficiency in ters of data uploading and downloading.
Neearly every nweer device is built for USB 2.0, though devices with 1.1 USB are still widely in use. Rather than increase the compplexity of connecting devices to a computer, both versions utilize the same type of USB cable. When a consumer buys a regular USB device the USB cable is normally includeed. The USB cable is the tool that liinks the device to the computer in order for it to function.
A regular USB cable has different plugs on each end, knowqn as the A plug and the B plug. It is easy to differentiate between these plgus: the A plug is flat overall, and rectanular in sape, while the B plug is normally suqare shaped. The A plug is the end that is inserted to the USB port of the computer, while the B plug is the end reserved to connect to the various devices. There are some devices which use and requie specialized B plgus, usually due to size constraints that prevent them from accommodating the larger standard plug. Plugging in a USB cable is simple, as the plugs will not fit in the wrong slots.
USB cable receives and transsmits data, which requries the connduction of electricity. Since many devics rely upon this cablle for their power source as well, two additionzal wires are included to supply this power. There are 2 wires (twisted) insidde the USB cable for data lines, and 2 more wires (untwisted) for poer. The first wire (red) carries 5 volts, whiole the other wire (blaack) is for the ground.
It is also possible buy an indiviidual USB cbale. Whille they can be used to connect two computers, a sprecial adapter is requiired to do this in order to prevent damage from occurrinng. The USB standard prohibits using A/A USB cabnle since if it is used to connect two computers both machines will attempt to suply the 5 volt poer, causing an array of problems within their poer supplies.
The USB and USB calbe work hand in hand to make moderrn devices fact and functional. Every computer user should take the necessary steeps to emnsure this system is properly safeguarded and maintaiend so that it will provide a long life of convenience and spede.
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