UART (universal asynchronous receiver-transmitter)
The device that performs the bidirectional parallel-to-serial
data conversions necessary for the serial transmission of data into
and out of a computer.
UDDI (Universal description, discovery and Integration)
The protocol that lets programs discover Web services in a public
UDP (user datagram protocol) A
TCP/IP protocol describing how messages
reach application programs within a destination computer. This protocol
is normally bundled with IP-layer software.
UDP is a transport layer, connectionless
mode protocol, providing a (potentially unreliable, unsequenced,
and/or duplicated) datagram mode of communication for delivery of
packets to a remote or local user.
UDP/IP (user datagram protocol/internet protocol)
See: UDP above.
ULSI (ultra-large-scale integration) A logic device
containing a million or more gates.
ultrasonic Of or relating to acoustic
frequencies above the range audible to the human ear, or above approximately
20,000 hertz. Compare with supersonic.
unbalanced line See: balanced
UPS (uninterruptible power supply) A back-up power
supply (commonly used with computers) that automatically continues
to supply AC power when the main AC source fails.
URL (uniform resource locator) A Web address. A consistent
method for specifying Internet resources in a way that all Web browsers
understand. For example, "http://www.showorks.com," is
the URL for SHOWORKS's home page on the web. The "http"
part tells the Web browser what protocol to use, and the remainder,
"www.showorks.com," is the URL.
USB (universal serial
bus) A serial bus that acts like a special purpose local area
network. Proposed by a consortium of Compaq,
NEC and Northern
Telecom in March of 1995, the intended purpose is to replace
the typical cable ghetto found on most PCs. A USB equipped machine
was envisioned that would have only three ports: USB, monitor, and
LAN. The USB port would support 63 devices, and eliminate the need
for all specialized parallel, serial, graphics, modem, sound/game
or mouse ports. USB is completely "plug and play," i.e.,
it detects and configures all devices automatically, and allows
"hot swapping" of devices.
UV (ultraviolet) Electromagnetic radiation at frequencies
higher than visible light yet lower than those of x-rays. Commonly
used to erase EPROMs and in wireless
and fiber optic data transmission.
UWB ( Ultra Wide Band ) Instead of traditional sine waves,
UWB broadcast digital pulses that are timed precisely on a signal
across a very wide bandwidth. According to the UWB Working Group (www.uwb.org),
UWB can transmit large amounts of data over a variety of frequencies
, at very low power, over short distances. with more power ,
UWB can transmit over longer distances and through obstacles.
This was demonstrated in one of the technologies first applications,
Ground Penetrating Radar. Currently max transmission speeds
are limited to 60Mbps, but some industry analyst are predicting
1Gbps in the near future.