Specifications

Glossary
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vacuum tube A device used to amplify or con-
trol electronic signals, it contains two major com-
ponents: a cathode (a filament used to generate
electrons) and an anode (a plate that captures elec-
tron current after it flows through one or more
grids). Largely replaced by the transistor and inte-
grated circuit in most small electronics applica-
tions, vacuum tubes in the form of CRTs are still
used to make conventional monitors. See also CRT.
VCPI (virtual control program interface) A
386 and later processor memory management stan-
dard created by Phar Lap software in conjunction
with other software developers. VCPI provides an
interface between applications using DOS extenders
and 386 memory managers.
vertex The corner of a triangle in 3D graphics.
The plural of vertex is vertices. See also vertex
shader.
vertex shader A graphics processing function
built into recent 3D graphics chips that manipu-
lates vertices by adding color, shading, and texture
effects. Recent GPUs such as the NVIDIA GeForce 3
and GeForce Ti and the ATI Radeon series incorpo-
rate vertex shaders. See also GPU, hardware shader,
and pixel shader.
vertical blanking interval (VBI) The top and
bottom lines in the video field, in which frame
numbers, picture stops, chapter stops, white flags,
closed captions, and more can be encoded. These
lines do not appear on the display screen but main-
tain image stability and enhance image access.
vertical scan frequency The rate at which the
electron gun in a monitor scans or refreshes the
entire screen each second.
very high frequency (VHF) The frequency
band between 30 and 300MHz.
very large scale integration See IC.
VESA (Video Electronics Standards
Association) Founded in the late 1980s by NEC
Home Electronics and eight other leading video
board manufacturers with the main goal to stan-
dardize the electrical, timing, and programming
issues surrounding 800×600 resolution video dis-
plays, commonly known as Super VGA. VESA has
also developed the Video Local Bus (VL-Bus)
standard for connecting high-speed adapters
directly to the local processor bus. The most recent
VESA standards involve digital flat-panel displays
and display identification.
VFAT (virtual file allocation table) A file
system used in Windows for Workgroups and
Windows 9x. VFAT provides 32-bit protected mode
access for file manipulation and supports long file-
names (LFNs)—up to 255 characters in Windows 95
and later. VFAT can also read disks prepared with
the standard DOS 16-bit FAT. VFAT was called 32-
bit file access in Windows for Workgroups. VFAT is
not the same as FAT32.
VGA (video graphics array) A type of PC
video display circuit (and adapter) first introduced
by IBM on April 2, 1987, which supports text and
graphics. Text is supported at a maximum resolu-
tion of 80×25 characters in 16 colors with a charac-
ter box of 9×16 pixels. Graphics are supported at a
maximum resolution of 320×200 pixels in 256
colors (from a palette of 262,144) or 640×480 pixels
in 16 colors. The VGA outputs an analog signal
with a horizontal scanning frequency of 31.5KHz
and supports analog color or analog monochrome
displays. Also refers generically to any adapter or
display capable of 640×480 resolution.
VHS (Video Home System) A popular con-
sumer videotape format developed by Matsushita
and JVC.
VIA Technologies A popular vendor of chipsets
for AMD Athlon and Intel Pentium 4–based sys-
tems; it’s also the maker of the VIA C3 processor.
video A system of recording and transmitting
primarily visual information by translating moving
or still images into electrical signals. The term video
properly refers to only the picture, but as a generic
term, video usually embraces audio and other sig-
nals that are part of a complete program. Video
now includes not only broadcast television but
many nonbroadcast applications, such as corporate
communications, marketing, home entertainment,
games, teletext, security, and even the visual dis-
play units of computer-based technology.
Video 8 or 8mm Video Video format based on
the 8mm videotapes popularized by Sony for
camcorders.
Appendix A
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