AT&T DataPort PCX Modem User Manual page 81

Glossary
RPI (Rockwell Protocol Interface)
A technique for modem/computer communication that permits
data compression and error control services to be provided by
the computer.
RS-232
An Electronic Industries Association's standard defining the
25-position interface between data terminal equipment and data
communications equipment.
RTS
Request To Send. A signal from the computer to the modem,
sent via Pin 4 of an RS-232 interface, that states the computer
has data to send.
RXD
Receive Data. Pin 3 of an RS-232 interface that is used by the
computer to receive data from the modem. Conversely, the
modem uses Pin 3 to transmit data to the computer.
S
S-register
A part of the modem's memory that contains values that
determine the modem's operating characteristics.
synchronous transmission
Data transmission that is synchronized by timing signals.
Characters are sent at a fixed rate. This type of transmission is
more efficient than asynchronous transmission.
Issue 2 July 1995
GL-9