VeriFone Omni 3200 Reference Manual page 179

Appendix C. Glossary
LRC. Longitudinal Redundancy Check. In the transmission of data
packets over a switched network, the LRC is a redundancy check
which is included at the end of each packet, following the ETX. This
check helps ensure that data received is the same as data sent. See
also 'ETX'.
Manual Transaction. A transaction involving the manual entry of
account information from the terminal keypad instead of automatic
entry of the information from a reading device, such as a card reader.
Memory. A device or medium that can retain information for
subsequent retrieval. The term is most frequently used to refer to the
internal storage of a computer (or a terminal) that can be directly
addressed by operating instructions.
Memory Dump. A procedure that shows the contents of a
terminal's memory at a specified point in time. This procedure is
sometimes used for debugging problems in program code.
Messages. Words and symbols appearing on the display panel
which inform the user of the terminal of the result of a process, or if
an error has occurred. (In this document, the term 'prompt' is used
when the displayed message is requesting the user to enter
information or to select an option.)
Modem. Short for 'modulator and demodulator'. A device that can
convert a digital bit stream into an analog signal suitable for
transmission over some analog communication channel (modulation),
and can convert incoming analog signals back into digital signals
(demodulation). The Omni 3200 internal modem lets the terminal
communicate with a host computer over a dial-up telephone line.
NAK. Short for 'negative acknowledgment'. In data
communications, a signal sent by the receiver as a negative response
to the sender to indicate that the previous block was unacceptable and
the receiver is now ready to accept a transmission.
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