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Brian Cryer's Glossary of IT Terms with Links

Analogue Modem

analogue modem

A modem for use with analogue equipment, such as a phone line. Typical analogue modem speeds are:

Modems can operate at speeds much slower than their rated maximum.

Where a cable modem has LEDs on the front, these are typically one or more of:

LED	Short for	Description
PWR	Power	Power-on/ready indicator.
MR	Modem Ready	Power-on/ready indicator.
AA	Auto Answer	Modem is ready to answer incoming calls.
CD	Carrier Detect	Indicates that the modem has detected a valid carrier signal from the remote modem. (When modems communicate they establish a carrier signal for handshaking purposes.)
HS	High Speed	Indicates if the connection is considered by the modem to be "High Speed" this is at the modem's top speed or above 4800bps (depending on the modem).
RD	Receive Data	Flashes when the modem is receiving data (from the modem at the other end of the link.)
SD	Send Data	Flashes when the modem is sending data (to the modem at the other end of the link).
TR	Terminal Ready	On indicates that the computer (that the modem is locally connected to) is ready to receive data.
DTR	Terminal Ready
CS	Clear to Send	On indicates that the modem is ready to receive data from the computer it is connected to.
CTS	Clear to Send
ARQ/FAX	Error correction fax
OH	Off Hook	Indicates that the phone line is active and the modem has control of the line.