Glossary
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National Instruments Corporation
G-9
NTSC
National Television Standards Committee. The committee that developed
the color video standard used primarily in North America, which uses
525 lines per frame. See also PAL.
NVRAM
Nonvolatile RAM. RAM that is not erased when a device loses power or is
turned off.
O
operating system
Base-level software that controls a computer, runs programs, interacts with
users, and communicates with installed hardware or peripheral devices.
P
PAL
Phase Alternation Line. One of the European video color standards; uses
625 lines per frame. See also NTSC.
PCI
Peripheral Component Interconnect. A high-performance expansion bus
architecture originally developed by Intel to replace ISA and EISA. PCI
offers a theoretical maximum transfer rate of 132 Mbytes/s.
PCLK
Pixel clock signal. Times the sampling of pixels on a video line.
PCLKIN
Pixel clock in signal.
PFI
Programmable function input.
PGIA
Programmable gain instrumentation amplifier.
picture aspect ratio
The ratio of the active pixel region to the active line region; for standard
video signals like RS-170 or CCIR, the full-size picture aspect ratio
normally is 4/3 (1.33).
pixel
Picture element. The smallest division that makes up the video scan line;
for display on a computer monitor, a pixel’s optimum dimension is square
(aspect ratio of 1:1, or the width equal to the height).
pixel aspect ratio
The ratio between the physical horizontal size and the vertical size of the
region covered by the pixel; an acquired pixel should optimally be square,
thus the optimal value is 1.0, but typically it falls between 0.95 and 1.05,
depending on camera quality.
pixel clock
Divides the incoming horizontal video line into pixels.
