3Com 3CP5610A User Manual page 62

56 C 5: G
HAPTER L OSSA RY
half duplex
Signals can flow in both directions, but only one way at a time. In
microcomputer communications, may refer to activation of the online
local echo, which causes the modem to send a copy of the transmitted
data to the screen of the sending computer.
Hz
Hertz, a frequency measurement unit used internationally to indicate
cycles per second.
Internet
An electronic communications network that connects computer networks
and organizational computer facilities around the world.
Internet Service Provider
A company which provides dial-up (modem) access to the Internet for a
fee.
ITU-T
An international organization that defines standards for telegraphic and
telephone equipment. For example, the Bell 212A standard for 1200-bps
communication in North America is observed internationally as ITU-T
V.22. For 2400-bps communication, most U.S. manufacturers observe
V.22 bis.
LAPM
Link Access Procedure for Modems. An error-control protocol defined in
ITU-T recommendation V.42. Like the MNP protocols, LAPM uses cyclic
redundancy checking (CRC) and retransmission of corrupted data (ARQ)
to ensure data reliability.
local echo
A modem feature that enables the modem to display keyboard
commands and transmitted data on the screen. See basic data command
En in the "Technical Reference" chapter of this manual.