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V-Bus
- Refer to Vitese Bus.
V.21
- A CCITT V series standard for full-duplex transmission at a speed of
300bps. This standard is used with dial-up lines (regular telephone
lines, making the connection by placing a telephone call). V21 is used in
Japan and Europe; in the United States, the Bell 103 standard is used
instead.
V.22
- A CCITT standard for
full-duplex transmission at a speed of 1200bps, over dial-up lines or
leased lines (telephone lines leased by private use). Leased lines
provide slightly wider bandwidth than dial-up lines, are faster and
quieter, but also are more expensive. Although V.11 is common in Europe
and Japan, the Bell 212A standard is more common in the United States.
V.22bps
- A CCITT V series
standard for full-duplex transmission at speeds of 1200bps or 2400bps
with dial-up or leased lines. This standard is world wide.
V.23
- A CCITT V series
standard for half-duplex transmission at speeds up to 1200bps on dial-up
or leased lines. This standard is worldwide.
V.26
- A CCITT V series
standard for full-duplex transmission at 2400bps over dial-up lines. This
standard is worldwide.
V.26bis
- A CCITT V series
standard for full-duplex transmission at speeds of 1200bps or 2400bps
over dial-up lines and is used world wide.
V.27
- A CCITT V series
standard for full-duplex transmission of 4800bps over leased lines.
Modems conforming to this standard have manual equalizers, which allow
them to compensate for distortion and delay so the signal reaches the
receiving device in its original form. This standard is used worldwide.
V.27bis
- A CCITT V series
standard for full-duplex transmission at speeds of 2400bps to 4800bps
over leased lines with automatic equalization. This standard is worldwide
V.27ter
- A CCITT V series
standard for full-duplex transmission at speeds of 2400bps to 4800bps
over dial-up lines. This standard is worldwide.
V.29
- A CCITT V series
standard used by fax modems for half or full duplex transmission at
speeds up to 9600bps over point-to-point leased circuits. This standard
is worldwide.
V.32
- A CCITT V series
standard for full-duplex modems transmitting data at 4800bps or 9600bps.
These modems adjust transmission speed automatically depending upon line
quality and have echo cancellation to remove the phone line echo.
V.32bis
- A CCITT V series
standard for modems transmitting at speeds up to 14,000bps over leased or
dial-up lines. An extension of the V.32 standard, this standard is
worldwide.
V.34
- A CCITT V series
standard for full-duplex transmission at speeds up to 28,800 bps. Modems
adhering to this standard automatically adjust their speed to compensate
for the quality of the phone line. This standard is worldwide.
V.42
- A CCITT V series
standard for regulating error-detection for high-speed modems. Modems
conforming to it can be used over digital telephone networks, as opposed
to the standard analog telephone networks. This standard is worldwide.
V.42bis
- A CCITT V series
standard for data compression that lets modems reach data transfer speeds
of up to 34,000bps. This standard is worldwide.
V86
mode - Refer to
virtual real mode.
V.90
- Agreement that came
to conclusion Feb 6, 1998 with the intension of getting KFlex56k and X2
to combine as one modem standard.
Vaccine
- Utility programs
that can protect computers from viruses.
Vacuum
tube - A glass tube
from which all gas has been removed, creating a vacuum. Such tubes
containing electrodes for controlling electron flow were used in early
computers (before semiconductors) as a switch or an amplifier. Vacuum
tubes allowed digital computations at what was then considered high
speed.
Validity
checking - To check
data, either through software or manually, to see if it adheres to
certain standards. A diskette could be checked for corrupted information,
or information could be checked to make sure it adheres to the standards
for a program, such as numbers falling within a designated range.
Value-added
network (VAN) - In
addition to being a simple communications network, a VAN offers users
additional services ranging from message routing to stock quote services.
Value-added
reseller (VAR) - A
company that sells computer systems with all the trappings. Typically, a
VAR buys hardware components and software based upon the client's needs
and installs the custom-made systems for a client. VARs also provide
after sale training and support.
VAN
- Refer to value-added
network.
Vaporware
- A satirical name
used to describe software that has been announced by a company but
apparently does not yet exist. It is often applied to new products
companies claim to be working on but no one outside the company has
actually seen. Also refers to products that have been passed their
announced ship date without appearing. Critics often accuse companies of
intentionally creating expectations for vaporware to keep customers from
buying competing products that are already available.
VAR
- Refer to Value-added
reseller.
Variable
- A common programming
concept in which a storage location contains data that can be altered by
the program whenever necessary. Just as in an algebraic equation, the
value of a variable such as X can fluctuate according to circumstances.
Variable
expression - Expression
that contains one or more variables, the values for which are not
constant. In the process of running the program, it must ascertain their
value.
Variable-length
field - Object with
adjustable length. In a database for example, a variable length TITLE
field means the field will be just long enough to accommodate each title.
VDT
- Refer to monitor.
Vector
- A line calculated in
either two dimensions or three dimensions and defined by its endpoints
which are coordinates in a grid.
Vector
font - Refer to
scaleable font.
Vector
graphics - Refer to
object-oriented graphics.
Vendor
ID - A number that
allows Plug-and-Play systems to identify an added device and configure it
properly. The number indicates the device's manufacturer, model, and
version number.
Version
- Number used to
indicate programs stage of development. Such as Version 1.0, being a new
release, and 1.5 being a later release update after 1.0.
Vertical
blanking interval - Refer
to vertical retrace.
Vertical
justification - Adjusting
the size of the space between lines to make the top and the bottom
margins equal. This feature is found mostly in word processing and
desktop publishing software.
Vertical
redundancy check (VRC) - Adding
a parity bit to a transmission to make it even or odd. By knowing whether
the final parity of the transmission should be even or odd, it can be
determined if the message is accurate.
Vertical
retrace - After the
electron beam has traced the entire screen to create an image, it travels
from the lower-right corner of a monitor to the upper-left. The beam is
turned off during the move, and this "down time" is called the
vertical blanking interval.
Vertical
scrolling - The
ability to move a document or spread sheet beyond the top and bottom of
the file.
Vertical
sync signal - Signal
in a display that indicates the electron beam has reached the end of the
last line at the bottom of the screen. The signal tells the beam to move
to the upper left corner of the screen.
Very-Large-Scale
Integration (VLSI) - An
integrated circuit design that contains 5,000 to 50,000 components on a
single chip.
Very
low frequency (VLF) - Describes
the electrical radiation emitted by computer monitors, televisions, and
other cathode ray tubes (CRTs).
VESA
- Refer to Video
Electronics Standard Association.
VESA
Local bus (VL-bus) - A
VESA created local bus that was up to 20 times faster than ISA (Industry
Standard Architecture) busses. The VL-bus was popular until the competing
PCI (Peripheral Component Interconnect) local bus architecture gained
widespread acceptance. VL-bus allows for "bus mastering" in
which smart adapter cards do some processing without the CPU; this
mastering can tie up the local bus and keep the CPU from using it. The VL-bus
standard lets up to three VL-bus slots, which each consist of an ISA,
EISA, or Micro Channel Architecture (MCA) connector plus a 16-bit MCA
connector, be built into the motherboard by the manufacture.
Vesicular
film - An optical disk
coating that lets information be stored in raised bumps rather than the
grooves traditionally used in CD-ROMs. Because the bumps can be
flattened, disks with vesicular film can be erased and rewritten. Grooves
on the other hand, cannot be overwritten.
VFAT
- 32-bit rewritten
code for the original FAT file system. Implemented into Windows 95. VFAT
is provided for Windows 95 to support long file names. Which is the
capability to assign file and directory names up to 255 characters in
length.
VGA
- Refer to Video
Graphics Array.
Video
accelerator - A video
adapter that contains a graphics coprocessor designed to handle graphical
computations better than the computer's CPU. The coprocessor increases
the speed of on-screen images and improves system performance by
relieving the CPU on the graphical tasks, letting it handle other tasks.
Video
adapter - A circuit
board in a computer that controls display factors such as resolution,
colors displayed, and speed of images displayed. A video adapter cannot
bring an older monitor up to its standard. Both the monitor and the video
adapter must support a resolution, such as 800 x 600, for that resolution
to be possible on the system. Today's video adapters typically contain
some memory so that PC's RAM isn't bogged down with handling displays.
Some adapters, often called video accelerators or graphics accelerators,
contain a graphics coprocessor that handles graphical computation. Also
called a video card, video board, or video controller.
Video
board - Refer to Video
adapter.
Video
buffer - A section of
memory that holds information before it is sent to the monitor. The video
buffer, also called a screen buffer or a regeneration buffer, is usually
a part of the video adapter.
Video
capture - To connect a
video camera or other device to a special video capture card that
translates the analog video signal into a digital data that can be
compressed, stored, and manipulated on the computer.
Video
card - Refer to video
adapter.
Videoconferencing
- A conference among
participants situated at different sites that are connected by video
cameras, microphones, and computer networks. Participants each sit in
front of the camera and microphone and view and listen to the other
participants as information is transmitted through the network to a
computer screen and speakers.
Video
controller - Refer to
video adapter.
Video
digitizer - A device
that captures video images such as those from videotape or television and
stores them as digital information with the aid of a special circuit
board.
Videodisk
- The predecessor to
the CD-ROM, videodisks originally were designed to store movies. They are
the size of an audio LP.
Video
display page - Before
a screen image is displayed on a monitor, it is held in this area of the
video buffer. Buffers can hold more than one page allow for quicker
display updates because one page can be displayed while another is being
filled.
Video
display terminal - Refer
to monitor.
Video
Electronics Standard Association (VESA) - Group of monitor and video card manufactures that set standards for
high-resolution monitors and video cards. Buying products that follow
VESA standards makes it easier to ensure all of a system's components
work together.
Video
For Windows - A common
Windows standard for storing video and audio information in multimedia
presentations. Many multimedia companies use Microsoft's Video For
Windows standard, which stores files in the .AVI format, because it
requires no special hardware and is widely accepted.
Video
graphics array (VGA) - Popular
display standard developed by IBM that provides 640 x 480 resolution
color display screens with a refresh rate of 60Hz and 16 colors displayed
at a time. If the resolution is lowered to 320 x 200, 256 colors can be
displayed VGA capability is built into plug -in video cards, VGA chips,
and monitors that can work with the VGA cards. See Video
Card for additional information.
Video
memory - Located on
the video card, video memory is accessible by both the video processor
and the CPU and is used to create images on a computer screen.
Video
mode - The state of a
video adapter. In general, this is either text mode, where the monitor
will display numbers, letters, and so forth, or graphics mode where the
monitor will show images.
Video
RAM (VRAM) - Special,
more expensive type of RAM chip that can perform reads and writes at the
same time, making it faster than dynamic RAM (DRAM). This means the chip
can send information to the monitor at the same time it receives new
information from a video processor. VRAM chips, which enhance graphics
performance, often are placed on video adapters to speed the creation of
on-screen images. Also called dual-ported memory.
Video
Signal - The signal a
video adapter sends to a display device to control an on-screen image.
Video
standards - The
various definitions of a PC's ability to display colors and resolution. A
PC supports a certain video standard only if both the monitor and the
video adapter support the standard. The numbers specified for a standard
often are minimums; many manufactures claiming to meet that standard
actually exceed the minimum numbers. See Video
Card for additional information.
Videotex
- Home information
service (most popular in Europe) in which subscribers use a keypad to
request information sent over telephone lines and displayed on a Videotex
screen or an ordinary television. The information, which is text and
simple graphics usually includes topics such as news, weather, and
shopping.
Viewer
- Utility for viewing
a file in its native format, which is the format of the program in which
it was created. Shell programs and file managers commonly offer viewers
for many file types. A single file viewer usually supports many document,
database, and spreadsheet file formats.
Virtual
- Used generally to
describe some thing without a physical presence or is not what it appears
to be. Virtual reality, for example is made up of computer-generated
images and sounds rather than actual objects. Virtual memory is a hard
drive acting as memory; it's not the physical chips used in real memory.
Virtual
8086 mode - Refer to
virtual real mode.
Virtual
address - The address
a program uses to reference data stored in a virtual memory situation.
Before the data is accessed, the memory management unit translates the
virtual address into a physical address.
Virtual
device - A device such
as hard drive space mimicking memory, that can be referenced even through
it doesn't actually exist. Virtual memory, for example, does not
physically exit on memory chips; its hard drive space mimicking memory.
Virtual
device driver (VxD) - Virtual
device drivers act as a simulation buffer between application and
hardware. The drivers sort out and ensure that the correct application
gets the information. With this setup, multiple applications can access
the same hardware with out causing conflict. In a device file name, V
means virtual and D means device.
Virtual
disk - Refer to RAM
disk.
Virtual
Image - Image
contained in memory that is too large to fit on the screen. Therefore
users scroll around the screen to bring portions of the image into view.
Virtual
machine - Software
imitating a physical device, such as the softwindows
program that allows users to run Windows programs on a Macintosh
computer.
Virtual
memory - A type of
hard drive space that mimics actual memory (RAM). When actually memory
space is limited, the use of virtual memory can let users work with
larger documents and run more software at once. When a program needs
information held in virtual memory address, the information is moved to
actual memory address.
Virtual
peripheral - A
make-believe device. Essentially, tricking the CPU into believing that a
device exists when actually it doesn't. For example, fax software can act
as a a virtual printer. When print is selected the document is sent to a
fax / modem, which then send information to another fax / modem or fax
machine instead of a printer printing the file.
Virtual
Reality (VR) - An
artificial, computer-generated environment in which users interact with
the environment and objects in it through specialized input devices such
as goggles, headphones, and gloves. Three dimensional images, moving
sound, and tactile feedback provided by the special gloves create
realistic situations when generated by high end computer system. Goggles
and wires also detect the user's movement so images and sounds change
relative to the head position.
Virtual
Reality Modeling Language (VRML) - Programming language that supports graphical animation of virtual spaces
on World Wide Web pages. Detailed three dimensional images can be created
with small programs, allowing the programs to arrive quickly at users'
computers and be viewed easily with special VRML browser applications and
or plug-in's.
Virtual
real mode - A feature
that lets Intel Corp.'s 386 and 486 chips operate as if they are several
8086 environments, each of which may run a different operating system. An
operating system or operating environment allows virtual real mode by
overseeing the operation of each 8086 environment. Software running in
each 8086 environment is independent of other environments and acts as if
it controls the entire system. Also called virtual 8086 mode or V86 mode.
Virus
- Program designed to
destroy or modify data, or cause other problems with the computer that
would other wise not be there. Virus's can be prevented by getting a
Virus protection program. For more extent information on Virus's see our Virus
Info page.
Visible
page - A graphics
image visible on the screen. Pages, or on screenful of information, are
the form in which information is stored in display memory.
Vitesse-Bus
- Bus interface that
communicates with a 64-bit data path at a rate of up to 66 Mhz and with
throughput around 4000 Mbps.
VL-bus
- Refer to VESA local
bus.
VLF
- Refer to very low
frequency.
VLSI
- Refer to Very
-Large-Scale Integration.
Voice
coil - A hard drive
head actuator that uses electromagnetic feedback from the disk's surface
to move the read/ write head the proper distance.
Voice-grade
channel - A
communications channel that can Cary speech and its commonly used for
transferring digital information at speeds up to 9600bps.
Voice
mail - An automated
telephone answering system in which callers choose options that help them
reach the voice mailbox of a particular person, then determine how a
message is recorded and delivered.
Voice
recognition - A
computer's ability to recognize spoke commands and act on them as if they
were keyboard or mouse commands. Voice recognition system do not
understand speech; that is done by natural language system. Even the best
voice (or speech) recognition programs, which can recognize thousands of
words, are speaker-dependent. This means the user must spend a lot of
time repeating words so that the PC is "trained" to recognize
their voices' particular tone, rhythm, speed, and pronunciation. Most
voice recognition programs are discrete speech programs, which allow
natural speech, will become more common in the future.
Volatile
memory - Memory whose
contents are erased when the system's power is turned off (on
interrupted). RAM is volatile, but ROM is not. It is because of RAM's
volatile nature that users must frequently save their work to a permanent
medium such as a hard drive to avoid losing data if the system's power is
interrupted.
Volume
- The amount of
storage on a storage medium, or the name of the medium itself. A single
diskette, for example may contain several volumes as in situations where
a hard drive is partitioned into several drives, each of which is a
volume.
Volume
label - A unique name
assigned to a storage medium usually at the time it is formatted.
DOS-based systems rarely use volume labels, but Macintosh systems
frequently refer to them on-screen volume names.
Volume
reference number - Refer
to volume serial number.
Volume
serial number - Number
assigned by operating systems such as MS-DOS to every diskette that is
formatted. Different from a volume label, it is used in situations such
as directory listings. Macintosh systems use a similar number called the
volume reference number.
Von
Neumann architecture - A
computer design approach that is key to the idea of stored programs,
which are stored in the PC and manipulated with instructions. This
architecture uses the idea of sequential processing in which one
operation is carried out at a time. With the development of parallel
architectures, which handle multiple operations at once, the Von Neumann
architecture began to get too crowded with data. This architecture was
designed by Hungarian mathematician John Von Neumann, who promoted it in
the 1940s.
Voltage
(Volt) - Unit of
electromotive force that causes current to flow in a circuit. One volt is
the amount required to send one ampere of current through a circuit with
one ohm of resistance.
Voltage
Drop - The difference
in potential between two points containing a circuit with impedance or
resistance.
VR
- Refer to virtual
reality.
VRAM
- Refer to video RAM.
VRML
- Refer to Virtual
Reality Modeling Language.
VSB
- Method for
modulating, or converting for transmission digital data over coaxial
cable. Created by Zenith, VSB has been chosen by the FCC as a standard
for digital TV.
VxD - Refer to virtual device driver.
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