Hardware Reference
In-Depth Information
ing connections to external displays. In short, DisplayPort is designed to be the ultimate
universal display interface for PCs now as well as in the future.
Previous digital display interfaces such as DVI and HDMI used TMDS, which requires
extra logic on both the source and display ends, logic that must usually be licensed from
SiliconImage.DisplayPortinsteadusesapacketized(network-like)interfacethatcaneas-
ily be implemented in chipsets without the extra cost logic required for DVI or HDMI.
DisplayPort is kind of like a high-speed Ethernet for video, and the network-like design
allows for features such as multiple video streams over a single connection, which means
you can connect multiple displays to a single port.
Because it is a license-free, royalty-free design, DisplayPort has seen rapid adoption
throughout the industry. In fact, all new chipsets and GPUs since 2008 from Intel,
NVIDIA, and AMT/ATI already have integrated DisplayPort support. In 2008, major
manufacturers including Dell, HP/Compaq, Lenovo, and Apple introduced products with
DisplayPortandendorsedDisplayPortasthesuccessortoDVIandHDMIformostdigital
display connections. Despite this endorsement, the introduction of DisplayPort-enabled
productshasproceededslowly.However,DisplayPortiscurrentlyavailableonanincreas-
ing number of laptops, 23 inch or larger LCD and backlit LED displays, computers, and
graphics cards for desktop and technical workstation use.
On the technical side, DisplayPort is a high-speed serial interface with up to four main
data lanes (differential signal pairs) carrying multiplexed video and audio data, each of
whichsupportsarawdatarateof1.62Gbps,2.7Gbps,or5.4Gbps(DisplayPort1.2orlater
only). Using all four lanes results in a maximum raw bandwidth of 6.48Gbps, 10.8Gbps,
or 21.6Gbps, respectively. Because 8b/10b encoding is used, only 8 bits of every 10 are
data,resultinginmaximumtruedatathroughputsof5.184Gbps,8.64Gbps,or17.28Gbps,
respectively.
Audio is optional, with support for up to eight channels of 16- or 24-bit linear PCM data
at a 48KHz, 96KHz, or 192KHz sampling rate, with an uncompressed maximum audio
bandwidth of 6.144Mbps.
DisplayPort 1.1 includes the following features:
• Small external connectors (slightly larger than universal serial bus [USB] size) with
optional latching. Four display connectors can fit on a single PCIe expansion card
bracket and fit easily in laptops.
• Cable lengths of up to 15 meters (49 feet), which allows for remote displays or pro-
jectors.
• Micro-packet network architecture over one to four lanes. Connections can use only
as many lanes as necessary for reduced wire counts.
