Radio Shack TRS-80 Manual page 11

Display Mode. To return to the Display Mode from the Print Mode,
turn the PRINT switch OFF and press the ON key twice.
This tells the Computer to check the PRINT switch on/off status. If it is
off, subsequent LIST and PRINT commands will output to the Computer
Display (not the Printer).
If you turn PRINT or POWER off while the Computer is in the Print Mode
and do not press the Computer's ON key twice, the next PRINT or LIST
operation will be ignored. However, commands after that will be
executed.
Note: Whenever the Computer is not connected to the Printer, you are
in the Display Mode.
3. Remote Switch
The REMOTE switch controls the Cassette Recorder when the Recorder
is connected to the Printer/Interface.
Note: The automatic line feed (on power-up) must take place before the
REMOTE switch will work.
REMOTE ON. When the REMOTE switch is ON, starting and
stopping of the Cassette Recorder is controlled by the Computer. (See
CSAVE and CLOAD in the Computer's Operation Manual.)
REMOTE OFF. When the REMOTE switch is OFF, you control the
starting and stopping of the Cassette Recorder by pressing the Cassette
Recorder keys.
(To connect the Cassette Recorder to the Interface, see "Connecting a
Cassette Recorder" in this Manual.)
4. Paper Advance Button
Press the Paper Advance Button once to advance the paper one line. Hold
down the button for continuous paper advance. If the paper does not
advance when you press the button, the battery is either low or the
POWER switch is OFF.
5. Low Battery Indicator
The LOW BATTERY indicator will begin blinking when the battery
becomes too weak to operate the Printer. When the indicator begins
blinking, input and output to/from the Cassette and Printer are disabled.
Printer and Cassette commands are then ignored.
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