Keyestudio 4DOF Manual page 86

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A- Used to verify whether there is any compiling mistakes or
not.
B- B- Used to upload the sketch to your Arduino board.
C- C- Used to create shortcut window of a new sketch.
D- D- Used to directly open an example sketch.
E- E- Used to save the sketch.
F- F- Used to send the serial data received from board to the
serial monitor.