ZyXEL Communications Omni 56K User Manual page 72

User's Guide for ZyXEL Omni 56K USB Modem
CDR Call Detail Record. This is a name used by telephone companies for call-related
information.
Cipher Text Text that has been scrambled or encrypted so that it cannot be read without deciphering it.
See Encryption.
Class 2 A standard for fax transfers using a fax modem. Currently several drafts exist which are
incompatible with each other. ZyXEL modems support the draft PN-2388 of August 20th
1990 and the final 2.0 standard.
Client A software program that is used to contact and obtain data from a Server software program
on another computer. Each Client program is designed to work with one or more specific
kinds of Server programs, and each Server requires a specific kind of Client. A Web
Browser is a specific kind of Client.
Call negotiation tone. A calling fax machine sends this tone before connecting to quickly
CNG
establish a fax connection. A data modem may also have a data calling tone.
(Central Office): a facility that serves local telephone subscribers. In the CO, subscribers'
CO
lines are joined to switching equipment that allows them to connect to each other for both
local and long distance calls.
Command Mode In command mode, a modem accepts commands from the local DTE. Data transfer is
suspended while the modem is in command mode.
If components are compatible, they work with each other.
Compatibility
COM Port Another name for the serial port on a PC.
See data compression.
Compression
Cookie A string of characters saved by a web browser on the user's hard disk. Many web pages
send cookies to track specific user information. Cookies can be used to retain information
as the user browses a web site. For example, cookies are used to 'remember' the items a
shopper may have in a shopping cart.
CRC Cyclic redundancy check; an error checking protocol.
Crossover A cable that wires a pin to its opposite pin, for example, RX+ is wired to TX+. This cable
Ethernet Cable connects two similar devices, for example, two data terminal equipment (DTE) or data
communications equipment (DCE) devices.
CTS/RTS Control signal lines on an RS-232C serial interface. These lines are needed to use hardware
flow control.
A special marker on a display.
Cursor
Data Bit In asynchronous transfers, a character is composed of data bits (the actual information) and
framing bits (start bit, stop bit/s, parity bit). The framing bits are needed to recognize
whether a character has been successfully transmitted and where a new character starts.
Re-coding of information. The same information is represented by less data bits. ZyXEL
Data
modems use MNP4 and V.42 compression schemes.
Compression
Data Packet Block of data that is framed by error control groups. A block consists of up to 256 8-bit
groups. Data packets are used in synchronous transfer.
The important module doing modulation and demodulation for a modem. The data pump is
Data Pump
B