Digital Video Interface (DVI)

By Stephen Bucaro

For many years computers used CRT (Cathode Ray Tube) displays. CRTs are an analog device, so the digital image data of the computer was converted to an analog signal based on VGA (Video Graphics Array) standard. Today's computers use LCD (Liquid Crystal Display) displays. LCDs are a digital device. It makes little sense to convert the digital image data to analog just to convert it back to digital to display on the LCD. To avoid this double conversion, the DVI (Digital Video Interface) standard was developed.

VGA Connector

DVI Connector

The DVI interface uses a different connector than VGA. In fact, there are four different versions of DVI connector.

DVI-A - DVI Analog is used to send a DVI signal to an analog display. This is for use in applications, such as vector graphics, where an analog display is preferable.

DVI-D - DVI Digital sends digital video at 165Mhz in a format called TMDS (Transition Minimized Differential Signaling). DVI-D also comes in a dual link connector that sends two TMDS video streams allowing display resolutions up to 2560 x 1600 pixels.

DVI-I - DVI Digital and DVI Analog Integrated has pins to send both digital and analog video signals. DVI-I also comes in a dual link connector that sends two digital streams.

DVI M1-DA - DVI Digital and DVI Analog and USB Integrated has pins for digital and analog video signals plus a USB channel. The USB portion of this connector is used to control equipment such a video projector.

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