Sony PCG-SR27 - Manual (Page 67)

Selecting the Display Mode
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4 Click the S3DuoVue tab and select the desired display device.
S3DuoVue Screen
✍
You may not be able to display the notebook LCD screen and an external display or
projector at the same time, depending on the types of computer displays and
projectors you are using.
The CRT option is disabled if an external computer monitor is not connected to the
external monitor connector.
Turn on the notebook after you turn on the peripheral devices.