DisplayPort: the new kid on the block has a bright future - Part 3 of 3

In Part 1 - Cost, I wrote about the inevitably of DisplayPort becoming the dominant display interface standard for PCs and handheld devices, if for no other reasons than cost:

1. DisplayPort avoids the $10k/year license fee of HDMI
2. DisplayPort direct-drive technology eliminates the cost for additional circuitry in computer displays

In Part 2 - Performance and Design, I reviewed some of the performance advantages of DisplayPort over DVI and to some degree, HDMI:

1. DisplayPort uses direct-drive technology, enabling ultra-thin displays and a setting a common standard for laptop and stand-alone displays
2. DisplayPort can drive 30-bit (billions) of colors at high-resolutions and high refresh rates
3. DisplayPort uses smaller, latching connectors and can handle longer cables
4. DisplayPort offers great flexibility in handling, video, audio and data

In this third installment I want to look at DisplayPort in terms of its potential for future digital devices relative to DVI and HDMI.

Futures

Unlike DVI or HDMI, both of which include legacy technology for CRTs, DisplayPort was designed specifically to handle today’s digital displays and to be able to adapt to new features in the displays and devices of the future.

The 45-nm Holy Grail of Chip Size
Chip makers from Intel to AMD to Nvidia are striving to reduce die size to 45-nm and smaller in order to reduce power consumption and increase transistor count. However, a 45-nm process imposes a technical limitation of 2.5V maximum for I/O transistors. HDMI and DVI both use TMDS, which requires 3.6V when running high-speed signals (up to 5.25V for low-speed sideband signals).

The only way around this limitation for HDMI and DVI is to add proprietary, custom circuitry. This translates into increased complexity and increased cost.

DisplayPort in contrast, requires less than 2V for high speed signals, so it can be integrated with a standard 45-nm process - no custom circuitry, no added size, and no additional costs.

Picture-in-Picture and Daisy Chained Displays
As already discussed in Part 2 - Performance and Design, DisplayPort was designed as all digital and uses micro packets to bundle audio, video, and data information. This micro-packet protocol is designed to support more than one audio or video stream, as well as data - all over a single cable. The current DP specification allows for up to six 1080i streams or three 1080p streams. So in the future you should expect to see things like Picture-in-Picture or daisy chained-monitors without additional cables or circuitry.

USB, Webcams, and Touch-Sensitive Displays
DisplayPort not only offers a scalable data channel, it offer a bi-directional scalable data channel. This means that future implementations will be able to support microphones, webcams, USB hubs, or touch-sensitivity built right into the display - without additional cabling and circuitry (this would be especially valuable on laptops where physical space is at a premium).

Dongles and Backwards Compatibility
DisplayPort may be the future, but since a lot of us are dealing with existing displays, laptops and consumer-electronics devices, there will be a need for adaptor cables or dongles to bridge between HDMI/ DVI and DisplayPort.

DisplayPort already offer pass-through support for HDMI signals. So using the appropriate dongle you can hook up your DVD player or cable box to a DisplayPort monitor. Coming later this year, expect to see adaptors that will allow you to connect your DisplayPort video card, to an HDMI or DVI device.

Final Score Card
So let me update my score card:

Feature	DVI	HDMI	DisplayPort
Price	+1	0	+2
Sleeker Displays	0	0	+2
Smaller Connectors	0	+2	+2
Resolution & pixel depth	+1	+2	+2
Long cables	0	+2	+2
Auto-tuning	0	?	+2
Audio	0	+2	+1
Smaller Chips	0	0	+2
Picture-in-Picture	0	+1	+2
Webcams & Touch Displays	0	0	+2
Compatibility	+1	+1	+1

While there is not a clear winner between HDMI and DisplayPort for today's market, in the near future the demands for the, cost benefits, performance, and scalable spec of DisplayPort will become more commanding. The FirePro line from AMD, as well as 30-bit color monitors from Dell and HP, are strongly embracing DisplayPort (but still hedging with at least one legacy DVI port) and I expect to see more card and display vendors move in this same direction next year.

Addendum: For the complete 3-part series on DisplayPort see:

• Part 1 - Cost
• Part 2 - Performance and Design
• Part 3 - Futures