Also on the top of the projector, you'll find the he control panel, which has all the basics. There are two concentric "rings" The outermost ring is essentially four buttons in the usual diamond shape. When using the menus, they are your up/down/left/right arrow buttons. When not in menu mode, the top and bottom arrows allow you to adjust keystone correction, the left arrow. More importantly the left button is your source select button. The right arrow does a computer re-sync to lock on to a computer source.
The inner ring consists of three buttons - the top left opens the menu (or closes it), and the top right is the Power/standby button. (the usual press once to power up, twice to power down). The whole lower semi-circle is the enter button. Further back are the typical three indicator lights - Lamp, Power, and Temp (from left to right).
That brings us to the input panel on the back. The Optoma HD71 is well endowed for a moderately priced 720p home theater projector. As you can see above, from right to left: 1 HDMI input (video and audio), one DVI-D (HDMI compatible, can handle HDMI, or DVI), VGA input (HD15) for analog computer. Below those there is a component video input (3 color coded RCA jacks), and below it the power cord receptacle.
On the left side, there are the obligatory S-Video and Composite video inputs as well as a USB input and an RS232 for command and control from PC or room controller. Below these, are a 12 volt trigger for a motorized screen or other 12 volt application, as well as three stereo audio inputs - one each for video/s-video, VGA / DVI-D, and component video inputs. (the HDMI connector handles audio from HDMI sources). That pretty much covers it on the back, except of course, for the Kensington lock slot.