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Vertical dot pitch
See Dot pitch.
Vertical scanning frequency
Expressed in Hz, this is the number of fields written to the screen every second in interlaced
mode. In non-interlaced mode vertical scanning frequency is the number of frames (complete
pictures) written to the screen every second (also known as refresh rate).
Vertical sync pulses
A train of square shaped waveforms that define the start of a new frame.
VESA
Video Electronic Standards Association, a consortium of manufacturers formed to establish and
maintain industry-wide standards for video cards and monitors. VESA was instrumental in the
introduction of the Super VGA and Extended VGA video graphics standards (see Video graphics
adapters) with a refresh rate of 70 Hz, minimizing flicker and helping to reduce operator eyes
fatigue and stress.
Video dot rate
See Dot rate.
Video graphics adapters
A card equipped with a character or graphic generator and video memory, which maps to the
screen. A microprocessor scans video memory and translates bit information from the computer
into displayable video signals for the monitor. These cards comply with various standards that
determine the nature and quality of the display.
VGA (Video Graphics Array), introduced in 1987, was the first analog card. It offered still higher
resolution than EGA: 640 X 480 pixels for graphics and 720 x 400 pixels for text, and a color
palette of 256 colors. VGA could also emulate EGA and CGA.
Super VGA, devised by VESA in 1989, offers a resolution of 800 x 600 pixels.
Extended VGA, introduced by VESA in 1991, offers a top resolution of 1024 x 768 pixels (non-
interlaced) and a refresh rate slightly higher than IBM's XGA 8514A.
High-end, graphics adapters, introduced over the last three years for professional workstations,
offer top resolutions from 1280 x 1024 to 1600 x 1280, horizontal line frequencies up to 90 kHz
and bandwidths up to 200 MHz.