DisplayPort is the first display interface to rely on packetized data transmission, a form of digital communication found in other technologies like Ethernet, USB and PCI Express. It allows both internal and external display connections, and unlike legacy standards where differential pairs are fixed to transmitting a clock signal with each output, the DisplayPort protocol is based on small data packets known as micro packets which can embed the clock signal within the data stream. The advantage is a lower number of pins to achieve higher resolutions. The use of data packets also allows for DisplayPort to be extensible, meaning additional features can be added over time without significant changes to the physical interface itself.
DisplayPort can be used to transmit audio and video simultaneously, but each one is optional and can be transmitted without the other. The video signal path can have 6 to 16 bits per color channel, and the audio path can have up to 8 channels of 24 bit 192 kHz uncompressed PCM audio which can encapsulate compressed audio formats in the audio stream. A bi-directional, half-duplex auxiliary channel carries device management and device control data for the Main Link, such as VESA EDID, MCCS and DPMS standards.
In addition, the interface is capable of carrying bi-directional USB signals. The DisplayPort signal is not compatible with DVI or HDMI. However, dual-mode DisplayPorts are designed to transmit a single-link DVI or HDMI protocol across the interface through the use of an external passive adapter that selects the desired signal and converts the electrical signalling from LVDS to TMDS. VGA and dual-link DVI, on the other hand, require active adapters to convert the protocol and signal to the desired output and do not require dual-mode DisplayPorts. VGA adapters are powered by the DisplayPort connector, while dual-link DVI adapters may rely on an external power source (see compatibility with HDMI, DVI and VGA).
The DisplayPort connector can have 1, 2, or 4 differential data pairs (lanes) in a Main Link, each with a raw bit rate of 1.62, 2.7, or 5.4 Gbit/s per lane with a self-clock running at 162, 270, or 540 MHz. Data is 8b/10b encoded where each 8 bits of information is encoded with a 10 bit symbol. So the effective data rates after decoding are 1.296, 2.16 and 4.32 Gbit/s per lane (or 80% of the total).