Radio Shack TRS-80 Model III Operation Manual page 21

ADD-ONS
Connecting Serial Interface Equipment
The Model II provides two serial I/O channels, for connection to equipment
like Telephone Interface Modems, Serial Line Printers, etc. Connection
instructions will be provided with the serial equipment. You can add such
instructions at the end of this Operation Manual. (See Specifications for a
description of the Serial Interface Signals.)
Figure 9. Radio Shack Telephone Interface II Modem
for connection of computer system to telephone line.
PARALI,..EL PRINTER
CHANNEL
SI . . . ······..·.. ·...
·.I?
"
..
:
........•.•.........
"",
~",;"
"
....
Figure 10. Connect Telephone Interface Modem (or other serial If 0 device) to serial
channel connection on the back panel of the video screen.
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