Radio Shack TRS-80 Model II Reference Manual page 128

MODEL II TRSDOS
Setting Up
For communications through ordinary telephone lines, you will need a
modem such as the Radio Shack Telephone Interface II, Catalog Number
26-1171, and the Model II RS-232 Cable, 26-4403.
1. Set up the modem according to its instructions, and connect it to
channel A on the back panel of the Model II display console. Unless
channel B is connected to another device, you must install the serial
terminator on that channel.
2. Find out what RS-232-C parameters are required by the host program you
are going to use:
Baud rate
Word length
Parity
Number of stop bits
You will need to initialize channel A accordingly (see "Running
Terminal").
3. Set the modem to originate or answer mode - whichever is different from
the mode used by the host program you are going to communicate with.
Also set it to full or half duplex, again depending on the requirements of
the host program.
4. Tum on the modem and the Model II computer system.
MODEL II
1
TELEPHONE INTERFACE
Figure 2. Connection ofModel II to a modem.
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