COURIER HIGH SPEED MODEMS
B-2 Summaries and Tables
THE RS-232 INTERFACE
DESCRIPTION
The RS-232 interface is a standard developed by the Electronic
Industries Association (EIA). It defines the signals and voltages
used when data is exchanged between a computer or terminal
and a modem or serial printer. Data is transmitted between the
devices via a cable with 25-pin, 9-pin, 8-pin or custom-built
connectors.
The modem takes a DB-25P (25-pin plug, or male) connector at
one end of the cable. Computer equipment varies, however.
Check the serial port at the rear of your machine, which may be
labeled SERIAL, COMM PORT, or some other term (e.g., RS-232). If
there are no labels, review your machine documentation to find
out which is the serial port. (There may be more than one.)
Don't use a port marked PARALLEL, PRINTER or AUX.
The physical serial port on the computer or terminal will be
either a socket (female) or plug (male) that typically accom-
modates 25 or 9 pins. For example, the port on the IBM PC,
PC/XT and most compatibles requires a DB-25S (socket) con-
nector, while the port on the IBM PC/AT and some compatibles
requires a DB-9S connector. Apple computers require a DB-
25P, DB-9P or, more typically, an 8-pin round plug connector.
Check your computer documentation or with your computer
dealer.
