For the Toshiba Satellite C855D-S5105, HDMI is an option.
If present, believe it to be on the Left side, same as the VGA port.
[General example of VGA connector (Port), and VGA Cable,http://en.wikipedia.org/wiki/VGA_Connector
Note* Color is not always Blue. Scroll down a little for VGA Cable example ]
User Manual states plug external monitor device into laptop, then turn external monitor device on.
External monitor device should automatically be seen by laptop.
If not press, and hold down on the Fn key, and at the same time, tap on the F4 key until the display option you want is shown. Then press the Enter key.
That requires a knowledge of Windows 8, which I do not have a full understanding of yet. The User Interface of Windows 8.
It isn't stated by Toshiba, (At least that I could find), as to if the HDMI port; is just that. An HDMI port, or a Mini-Port HDMI port,http://en.wikipedia.org/wiki/File:HDMI_Connector.jpg
There are HDMI adapters, and HDMI cables; that adapt from regular HDMI to Mini-Port HDMI.
There are adapters that connect to a VGA port, and convert to an HDMI port.
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