Multitech CommPlete MT5634HD8, User Manual, Page: 82 / 99

MT5634HD8 User Guide
76 CommPlete Communications Server
DB-25 : A very common 25-pin connector often
referred to as an RSs-232 connector because it is
the connector over which the RS-232 interface
commonly occurs.
DB (Direct Current) : Usually understood to
mean a constant voltage supply that fluctuates
only a nominal amount. An analog or digital
signal that may vary in voltage level, but it
never crosses the reference voltage (usually
called ground). Contrast with AC>
De facto standards : A de facto standard is one
of two types of voluntary standards recognized
by a given market. It is introduced by a single
vendor and becomes a standard by its
widespread use and acceptance by other
vendors. AT&T’s Bell 212A, IBM’s Binary
Synchronous Protocol, or DEC’s VT-100 terminal
protocol are examples of de facto standards.
Compare with de jure standards.
De jure standards : A de jure standard is one of
two types of voluntary standards. It represents
the collective consensus of the industry and
users for a particular aspect of manufacturing.
CCITT’s V and X standards (V.32 and Xx.25) are
examples of de jure standards. Compare with de
factor standards.
Decibel (dB) : A unit of measurement for signal
strength based on logarithmic increments, A
decibel is a relative measurement that is
derived from an initial reference level and a
final observed level.
Default : A preset value or option, in software
packages, or in hardware configuration, that is
used unless you specify otherwise.
Device driver : Software that controls how a
computer communicates with a device, such as a
printer or mouse.
Digital signal : Digital devices, such as
terminals and computers, transmit data as a
series of electrical pulses which have discrete
jumps rather than gradual changes.
Digital Transmission : A method of electronic
information transmission common between
computers and other digital devices. Analog
signals are waveforms: a combination of many
possible voltages. A computer’s digital signal
may be only “high” or “low” at any given time.
Therefore, digital signals may be “cleaned up”
(noise and distortion removed) and amplified
during transmission.
DIP switch : A set of tiny toggle switches, built
into a DIP (dual in-line package), used for
setting configurable parameters on a PCB
(printed circuit board).
Directory : A logical subdivision of a
computer’s disk space used to organize a group
of files. A directory can be thought of as a file
drawer.
DOS (Disk Operating System - pronounced
“daws”)
: The software that allows all the
hardware in a PC to interact. The basis for
(DOS prompt) higher level applications.
DOS prompt : The > symbol displayed after
the disk drive letter.
DPSK (Differential Phase Shift Keying): A
common form of phase modulation used in
modems. It does not require complex
demodulation circuitry and is not susceptible to
random phase changes in the transmitted
waveform, thus reducing errors during
transmission.
Driver : A software module that interfaces
between the Operating System and a specific
hardware device, such as a color monitor,
printer or hard disk. Also known as a device
driver.
DSR (Data Set Ready) : An RS-232 signal sent
from the modem to the computer or terminal
indicating that it is able to accept data.
Contrast with DTR.
DTE (Data Terminating Equipment) : A term
used to include any device in a network which
generates, stores, or displays user information.
DTE is a telecommunications term which
usually refers to PCs, terminals, printers, etc.
DTMF (Dual-Tone MultiFrequency) : A
generic push-button concept made popular by
AT&T TouchTone.
DTR (Data Terminal Ready) : An RS-232 signal
sent from the computer or terminal to the
modem indicating that it is able to accept data.