Sony PCG-GR250 - Manual (Page 71)

Connecting an External Display
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Use the Fn+F7 keys to select a display. See also “Selecting the Display Mode” for
more information.
To Press Result
Switch to an
external display Fn+F7 Toggles between the LCD, the external display
connected to the Monitor port, or both the LCD
and external display.
✍
Connect the cable before you turn on the notebook, otherwise Fn + F7 will not work.
Only LCD LCD and external display
Only external display