34
6179-2201
NVRAM
Non Volatile Random Access Memory. Consists most often by an EEPROM (Electronically Eraseable
and Programmable memory). Used by the modem to store profile information and numbers even
when the unit has no power.
Normal Mode
A non error corrected connection, where data is buffered.
Off Hook
Like picking up the receiver. Connecting to a line.
On Hook
Like hanging up the receiver. Disconnecting.
PSTN
Public Switched Telephone Network, i.e. a normal telephone line on which other subscribers can be
called.
Parity
A mathematically derived bit which is added by the transmitter. The receiver checks it to detect any
error in transmission. Occurring parities are even, odd and none.
REN Number
The Ringer Equivalence Number (REN) is a way of measuring the load on the telephone line caused
by the connected equipment.
RS-232/V.24 Signals
TD
Transmitted Data. Data going from DTE to DCE.
RD
Received Data. The Data going from DCE to DTE.
RTS
Request To Send from DTE.
DSR
Data Set Ready. The DCE-equipment is powered and usable.
DTR
Data Terminal Ready. The DTE-equipment is powered and usable.
DCD
Data Carrier Detect. A signal from the DCE indicating that a carrier is present on the line.
Simplex
Uni-directional communication.
Start bit
Marks the start of a character at asynchronous communication.
Stop bit
One or more stop bits marks the end of a character at asynchronous communication. Systems that
require more than one stop bit may have problems during communication via modems, since modems
most often remove the second stop bit.
