Radio Shack TRS-80 PC-3 Owner's Manual page 24

(7) Push the back cover in slightly while replacing the screws.
(8) Turn on the computer by setting the power slide switch to the ON position and press the RESET button to clear the computer.
Then check the following display.
DEG
~
Prompt symbol
Figure
13.
Sample Display On Start-Up
If the display is blank or displays any symbol other than the prompt" ..:- ", remove the batteries and install them again.
Then check the display again.
NOTE:
Keeping a dead battery may result in damage to the computer due to solvent leakage of the battery, Remove a dead battery
promptly.
CAUTION: Keep battery out of reach of children.
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