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UART
- Refer to Universal
Asynchronous Receiver-Transmitter.
UART
Overrun - A condition
that occurs when a universal asynchronous receiver-transmitter (UART)
can't process one byte of information before another one arrives. The
first byte then disappears, causing a communications error. To avoid this
problem, a PC's configuration should be set to a 16-byte buffer instead
of the typical one-byte buffers, letting these temporary memory storage
areas hold more information. The 16550 is a UART with a 16-byte buffer.
Ultralight
computer - Another
term for a portable computer, which is a type of computer that can be
transported easily from place to place. An ultralight PC weighs between 2
pounds and 8 pounds and usually can fit in a briefcase. These computers
are powered by either a battery or a transformer pack. Some of these
systems use a RAM drive instead of a hard drive or diskette drive.
Ultra-large-scale
integration (USLI) - The
density of transistors on an integrated circuit (computer chip) and the
degree of connections' fineness between circuits. ULSI usually applies to
any integrated circuit with more than 10 million transistors. This type
of integration allows chip manufactures to get more transistors on one
tiny piece of silicon.
UMA
- Refer to Upper
Memory Area.
UMB
- Refer to Upper
Memory Block.
Unarchive
- To restore files
from an archive or backup to their original location, usually a hard
drive.
Unbundled
- Software or hardware
that once was included with several other products (a bundle) but was
removed from the packaging or is sold separately.
Undelete
- To restore a deleted
file using a utility program such as Norton Utilities or by using the
UNDELETE command in DOS 5.x and newer. Deleted files are not actually
erased until the storage area where they reside is needed for another
file. Therefore, it is sometimes possible to undelete a file. Also called
un-erase.
Undercolor
separation - Using the
CMY color model to covert cyan, magenta, and yellow to equivalent grays
when printing a color document. This separation produces higher quality
grays than grays produced when cyan, magenta, and yellow are mixed. The
CMYK color model adds black to cyan, magenta, and yellow to make richer
black hues.
Underflow
- A mathematical
calculation that results in a number so close to zero that a computer
cannot represent it using binary digits. Some systems will give the user
an error message if this occurs; while other computers will guess at the
number and go on.
Underline
- A section of text in
a document where the words have a line running beneath them. Underlining
is usually done in either word processing or desktop publishing packages
and can consist of single lines, double lines, or dotted lines.
Underscore
- A character in a
document that is underlined. The underscore usually denotes emphases on a
letter or word. Example of underscore _.
Undo
- A command that
reverses the action mostly recently completed. Some programs, however,
let several commands be undone at once. Whenever a user chooses the undo
button in a word processing program, the previous command is undone. For
example, if a section of the document is changed or deleted and then the
user wants the original back, the undo feature will retrieve the deleted
information.
Undocumented
- Any information that
isn't found in printed documentation accompanying a product. This is
usually data that programmers didn't think user needed, or it might cover
untested features in a product.
Un-erase
- Refer to undelete.
Unicode
- Represents
characters as integers in lines of computer code. This standard is
different from ASCII in that it uses two bytes (16 bits) for each
character instead of one byte (eight bits). This allows Unicode to
represent more than 65,000 characters as opposed to the 256 that the
American Standard Code for Information Interchange (ASCII) can handle,
making it capable of producing the appropriate characters for most
languages. This feature isn't important in English because all English
characters can be represented by ASCII. For the non-Roman languages,
however, such as Japanese and Chinese, Unicode lets all characters in
those languages be represented by rearranging the 16 bits into different
formats.
Uninterruptible
Power Supply (UPS) - A
generator connecting a PC to the power supply that provides back up power
for a computer system in case of a power outage (blackout), brownout, or
a power surge. A UPS contains a battery and provides power for a short
time, usually long enough for the original power source to be restored or
for users to save their work to their hard drive and shut the system down
safely. Many UPSes now are bundled with software packages that can
automatically save work and power down the system if the user is away
from the PC when the outage occurs. Two types of UPSes are available.
One, a standby power system (SPS) or offline system, monitors power line
activity and will switch the system to battery power if something goes
wrong. This switch can take several milliseconds, stopping power from
traveling to a PC during this time. The other, more expensive option, an
online UPS system, will give a PC constant power from an inverter or
batter, even if a problem is found in the line.
Unipolar
- A device that uses
the same voltage polarity (either positive or negative) to represent
binary states, such as on or off.
UNIVAC
I (Universal Automatic Computer) - The first electronic computer made commercially available that could
process numbers and text. The design was bought from J. Prosper Eckert
and John Mauchly in the early 1950s by Remington Rand, which became the
world's first large scale computer company. The company sold 46 of these
computers to government and industry. In 1952, this machine produced
results that predicted Dwight D. Eisenhower's victory over Adlai
Stevenson for the U.S. presidency. This event made UNIVAC synonymous with
the term "computer."
Universal
asynchronous receiver-transmitter (UART) - The most common type of circuit used to connect modems and manage serial
ports, converting bytes into serial bits that can be transmitted. The
UART also converts incoming serial data into parallel data so it can be
received. The difference between UART and universal synchronous
receiver-transmitter (USRT) is that UART module has both the receiving
and transmitting circuits needed for asynchronous serial communication,
which is when two modems rely upon the other to send start and stop
signals to set the pace for information exchange. Without this, the
modems can't detect when packets of information begin and end because
this process doesn't rely upon clock signals.
Universal
Product Code (UPC) - A
bar code found on many retail products used by business computer systems
to track inventory and provide point-of-scale automatic pricing.
Computers can read the bar code with a scanning device and translate the
data into a number.
Universal
Resource Locator - A
standardized naming, of "addressing," system for documents and
media accessible over the Internet. For example, the URL http://www.computerhope.com
includes this type of standardization.
Universal
Serial Bus (USB) - Standard
that started in 1995 by Intel, Compaq, Microsoft and several other IT
computer companies and begin showing up in some computers in 1996. In
1997, USB became popular and widespread with the release of Intel's 440LX
chipset. External Bus standard that supports data transfer rates of 12
Million bits per second. A single USB device is capable of supporting up
to 127 peripheral devices using both isochronous and asynchronous data
transfers.
Universal
synchronous receiver transmitter (USRT) - Circuit in which both the receiving and transmitting circuits are built
into a single integrated circuit, allowing for synchronous serial
communication. This type of communication doesn't require start and stop
coding to be placed in every package of data sent because the receiving
unit automatically understands when data packets start and stop.
UNIX
- A powerful operation
system developed by AT&T Bell Laboratories in 1969 and used primarily
by universities and mid-sized businesses. Written in the C programming
language (which is popular for PC because it takes up less memory to use
than other languages), this multi-user, multitasking operating system was
designed for both large mainframes and minicomputers. It can be used on
many platforms and can run a wider variety of hardware than other
operating systems. This operating system is more popular for workstation
computers on networks rather than individual PCs.
Unload
- The process of
removing a program from memory. This procedure is most useful when
dealing with terminate-and-stay resident programs (TSRs), which load into
memory and reside there, using space even if they're not being used.
Unmount
- To stop a computer
from accessing diskettes or tape.
Unpack
- To restore
compressed information to its original form. This term also refers to the
way database programs mark entries for deletion.
Unpopulated
board - A circuit
board, found inside a PC, containing empty sockets.
Unprintable
character - A hidden
command in a document that will not be printed when the document is sent
to the printer, because it usually represents formatting commands that
tell the program to perform functions such as return and indent. Examples
of these characters include the TAB, ENTER, and ALT, and CTRL keys.
Unrecoverable
error - An error that
occurs during a PC's operation that no number of retries can correct.
Unshielded
Twisted Pair (UTP) cable - Popular
type of cable used in networking that consists of two shielded wires
twisted around each other. Because UTP cable is generally a low cost and
low bandwidth cable it is usually found within LANs and telephone
connections.
Unzip
- To decompress a file
with a utility such as PKUNZIP. During the unzipping process the one
large file(s) is decompressed and extracted into several files.
Up
- Signifying that the
system, program, or printer in question is working and ready to be used.
UPC
- Refer to Universal
Product Code.
Update
- To replace older
versions of software or files with a newer version. Also refers to when a
company releases a new version of software that's already on the market
this is usually indicated by a change in the version number, such as 1.1
to 1.2.
Upgrade
- To change a system
or program to a new version of a specific hardware or software product.
Usually, companies will provide registered users with the more powerful
upgrade of a product at a discounted price to keep them as customers.
Upload
- To transfer an
application of file to another computer through a modem or network.
Upper
memory area (UMA) - The
area of RAM between 640KB and 1,024KB (1MB) that has been made into
usable RAM. In DOS based systems, memory is split into five areas;
conventional memory, upper memory, high memory, extended memory, and
expanded memory. The UMA consists of upper memory blocks, and users can
access this area through a special memory manager, such as EMM386.exe
Upper
memory block (UMB) - Many
times, certain areas of upper memory are remapped into RAM that can be
used. After this happens, terminate-and-stay-resident programs (TSRs) and
device drivers can be loaded into these blocks to free conventional
memory for use by other programs.
Uppercase
- A capital letter,
such as A, B, C.
UPS
- Refer to
Uninterruptible power supply.
Upstream
- A point on a
network's hierarchical tree from which data "flows" down to
users. For example a file server to which an end user is connected to
upstream for the end user's workstation.
Uptime
- The length of time a
user can work on a computer before being interrupted.
Upward
compatible - The
ability of devices and programs, usually software, to recognize and use
technologically advanced systems that will become standard in the future.
For example, many programs designed for the 80486 CPU also can be used on
a Pentium system. These products are attractive to users because when
they upgrade to a newer computer system they won't have to transfer all
their files to new programs. Also called Backwards compatible.
URL
- Refer to Universal
resource.
Usability
- Describes the ease
or difficulty of using a product for a specific task if a product has
high usability, for example, it means that it's flexible, is easy to
learn how to operate because of its good design, and is essentially free
of problems or bugs.
USB
- Refer to Universal
Serial Bus.
Usenet
- A giant bulletin
board on the Internet consisting of user news, E-mail, and forums that
discuss thousands of topics. Usenet newsgroups can be accessed through
the Internet or other online services with a modem. Users can communicate
on this Unix network by posting a message about a topic then waiting for
a response. Started in 1979 this network was used as a bulletin board
between two universities in North Carolina and has grown into a large
public access area.
User
- Any nonprofessional
person (those who don't program computers or provide technical support
for them) who works with PC's.
User
account - An
individual set of parameters and profiles designed for one user of a
multi-user system, such as for each family member using a home PC. It
often consists of information about the user, such as the user's name and
the password required to access the system, in addition to information
about which files and programs the individual can use.
User-friendly
- A program or system
that can be learned and used with relative ease. An example of a
user-friendly operating system is Microsoft Windows
98.
User
group - Consists of a
group of people with similar computer interests, either about hardware of
software, who exchange ideas and PC tips to improve their understanding
of a product. These gatherings either can cover a broad range of topics
with subgroups called specialized interest groups or SIGs for more
specialized interests or can concentrate on specifics, such as certain
movie or television show.
User
interface - The part
of the software that user works with, whether it be through commands or
menus. Interface can be either text-driven, such as DOS, or graphical
user interfaces (GUIs), such as Windows.
User
name - A code used by
individuals, in addition to a password, that lets them access a network
computer, an online service or a bulletin board system. Most of the time
users select their own user names and passwords.
User
profile - A set of
personalized parameters that contain information about a person's
electronic mailbox location and access rights. Normally used for security
purposes, each authorized user or a network or multi-user PC must have
one of these, often used in conjunction with a user name and password.
USRT
- See Universal
synchronous receiver-transmitter.
Utility
- Software designed to
perform certain housekeeping tasks, such as those related to managing
system resources and file capabilities.
UTP - Refer to Unshielded Twisted Pair
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