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Glossary
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National Instruments Corporation G-5 PCI-6023E/6024E/6025E User Manual
dB decibel—the unit for expressing a logarithmic measure of the ratio of two
signal levels: dB=20log10 V1/V2, for signals in volts
DC direct current
DC coupled allowing the transmission of both AC and DC signals
DGND digital ground signal
DIFF differential mode
differential input an analog input consisting of two terminals, both of which are isolated from
computer ground, whose difference is measured
digital port See port.
DIN Deutsche Industrie Norme
DIO digital input/output
dithering the addition of Gaussian noise to an analog input signal
DMA direct memory access—a method by which data can be transferred to/from
computer memory from/to a device or memory on the bus while the
processor does something else. DMA is the fastest method of transferring
data to/from computer memory.
DNL differential nonlinearity—a measure in least significant bit of the
worst-case deviation of code widths from their ideal value of 1 LSB
DO digital output
drivers software that controls a specific hardware device such as a DAQ board or
a GPIB interface board
E
EEPROM electrically erasable programmable read-only memory—ROM that can be
erased with an electrical signal and reprogrammed
electrostatically coupled propagating a signal by means of a varying electric field
external trigger a voltage pulse from an external source that triggers an event such as A/D
conversion
PCI.book Page 5 Wednesday, September 16, 1998 9:09 AM