|Today just about every PC comes with
Universal Serial Bus, or
ports. In fact, many computers will even have additional USB
ports located on the front of the tower, in additional to two
standard USB ports at the back. In the late 1990s, a few computer
manufacturers started including USB support in their new systems,
but today USB has become a standard connection port for many devices
such as keyboards, mice, joysticks and digital cameras to name
few USB-enabled devices. USB is able to support and is supported by a large range of
Adding to the appeal of USB is that
it is supported at the operating system level, and compared to alternative ports such as
serial ports, USB is very user-friendly. When USB first started
appearing in the marketplace, it was (and still is) referred to as a
plug-and-play port because of its ease of use. Consumers without a
lot of technical or hardware knowledge were able to easily connect
USB devices to their computer. You no longer needed to turn the
computer off to install the devices either. You simply plug them in
and go. USB devices can also be used across multiple platforms. USB
Mac, plus can be used with other operating
systems, such as Linux, for example, with
a reliable degree of
Before USB, connecting devices to your system
was often a hassle. Modems and digital cameras were connected via the
serial port which was quite slow, as only 1
bit is transmitted at
a time through a serial port. While printers generally required a
parallel printer port, which is able to
receive more than one
bit at a time that
is, it receives several bits in parallel. Most systems provided two
serial ports and a parallel printer port.
If you had several devices, unhooking one device and setting up the
and drivers to use another device
could often be problematic for the user.
The introduction of
USB ended many of the headaches associated with needing to use serial ports and
parallel printer ports. USB offered consumers the option to connect up
to 127 devices, either directly or through the use of a USB
hub. It was much
faster since USB supports data transfer rates of 12 Mbps for disk drives and
other high-speed throughput and 1.5Mbps for
devices that need less bandwidth. Additionally,
consumers can literally plug almost any USB device into their
computer, and Windows will detect it and automatically set-up the hardware
settings for the device. Once that device has been installed you can remove
it from your system and the next time you plug it in, Windows will
automatically detect it.
Key Terms To
Short for Universal Serial Bus, an external bus standard that
supports data transfer rates of 12 Mbps.
Also referred to as Hi-Speed USB, USB 2.0 is an external bus that
supports data rates up to 480Mbps. USB 2.0 is an extension of USB
Short for USB On-The-Go, an extension of the USB 2.0 specification
for connecting peripheral devices to each other. USB OTG products
can communicate with each other without the need to be connected to
More USB Related
external data bus
data transfer rates
First released in 1996,
the original USB 1.0 standard
offered data rates of 1.5 Mbps. The USB 1.1 standard followed with two data rates: 12 Mbps for devices such as
disk drives that need high-speed throughput and 1.5 Mbps for devices such as
joysticks that need much less bandwidth.
In 2002 a newer specification
USB 2.0, also
called Hi-Speed USB 2.0, was introduced. It increased the data transfer rate
for PC to USB device to 480 Mbps, which is 40 times faster
than the USB 1.1 specification. With the increased bandwidth, high
throughput peripherals such as digital cameras, CD burners and video
equipment could now be connected with USB. It also allowed for multiple
high-speed devices to run simultaneously. Another important feature of
USB 2.0 is that it supports Windows XP through Windows update.
USB On-the-Go (OTG) addresses the need for devices to communicate
directly for mobile connectivity. USB OTG allows consumers to connect
mobile devices without a PC. For example, USB OTG lets consumers
plug their digital camera directly into a compliant printer and print
directly from the camera, removing the need to go through the computer.
Similarly, a PDA keyboard with
a USB OTG interface can communicatea with any brand PDA that has a
USB OTG interface.
USB-OTG also provides limited host capability to
communicate with selected other USB peripherals, a small
USB connector to fit the mobile form factor and low power features to
preserve battery life. USB OTG is a supplement to the USB 2.0 specification.
Types of USB Connectors
Currently, there are four types of USB connectors: Type A, Type B,
mini-A and mini-B and are supported by the different USB specifications
(USB 1, USB 2 and USB-OTG).
Often referred to as the downstream connector, the Type A USB connector
is rectangular in shape and is the one you use to plug into the CPU or USB
Also called the upstream connector, the Type B USB connector is more
box-shaped and is the end that attaches directly to the device (such as
a printer or digital camera).
specifies the Type A and Type B.
USB 2.0 connector was too large for many
of the new handheld devices, such as PDAs and cell phones. The mini-B
was introduced to enable consumers to take advantage of USB PC
connectivity for these smaller devices.
specifies the Type A, Type B and mini-B.
With the need to connect mobile devices without the aid of a
computer, the mini-A port was designed to connect the new generation
of smaller mobile devices.
USB OTG specifies the
With an estimated 2 billion plus USB connected devices in the world and a
growing interest in wireless computing, it's no surprise that development
has turned to wireless USB. The USB Implementers Forum has introduced
Certified Wireless USB the newest extension to the USB technology. Wireless
USB applies wireless technology to existing USB standards to enable wireless
consumers to still use USB devices without the mess of wires and worry of
cords. Still in its infancy, the Wireless USB specifications were
made available to the public only in May 2005.
Wireless USB is based
on the WiMedia MAC
Convergence Architecture, using the WiMedia Alliance's MB-OFDM
MAC and PHY. It delivers speeds equivalent to wired Hi-Speed USB, with
bandwidths of 480Mbs at 3 meters and 110 Mbs at 10 meters.
Did You Know...
USB was introduced in 1997 but the technology didn't catch on until the introduction of the Apple iMac in 1998 ironic because USB was developed by several PC-focused
companies, including Compaq, DEC, IBM, Intel and Microsoft.