Changing face of PC displays

There’s very little you can plug into a PC from 20 years ago that will still connect to a modern system, but one item remains that’s well past its sell-by date – the humble 15-pin D-sub VGA connector.

It may have been better than its predecessors, but the VGA connector is a terrible match for modern display technology. But still it remains, unchanged, on the back of most PCs.

VGA was designed for analogue video signals, and most of us now use digital flat panels. So we have the bizarre situation where your PC produces digital images that are converted to analogue signals, then sent through a VGA cable and converted back to digital again for display on your monitor.

Thankfully, a little over 10 years after the introduction of VGA, the Digital Display Working Group (DDWG) gave us the Digital Visual Interface standard, or DVI.

DVI is a standard interface for connecting digital displays to computers. Proprietary designs had existed before, usually in the form of monitors with their own dedicated graphics cards, but DVI allowed us to ‘mix and match’ PCs and digital monitors.

Better still, because the most highly specified version of DVI – DVI-I – supports digital and analogue signals, simple cheap adapters can connect DVI-I graphics cards to monitors fitted only with VGA connectors.

Who needs a new standard?
Can DVI do everything we need? It offers digital connectivity while maintaining compatibility with analogue displays, it can cope with HD resolutions and it can support the latest content-protection schemes. More importantly, most modern PCs and monitors are already fitted with the connectors.

But – as is so often the case in computing – bandwidth is a problem. If you’re lucky enough to own a 30in TFT monitor, such as those from Dell and Apple, then you’ll need to run your display at a resolution of 2,560x1,600 pixels to get the best out of it, and that resolution already exceeds the bandwidth of a single DVI connection.

These displays use DVI’s optional dual-link mode, which doubles the available bandwidth. Dual-link connections require the graphics card, monitor and DVI cable to adhere to the dual-link specification; unfortunately, in the real world you have to try very hard to make this happen.

With more and more people using PCs as media centres, many computers are plugged straight into TVs. DVI has no provision for the transmission of audio, meaning your speakers will have to be connected with their own cabling – even if they’re built into your TV or flat-panel display, potentially adding more mess and inconvenience when you hook everything up. And modern multichannel audio requires even more bandwidth and content-protection abilities.

So, let’s look at the standards competing in the world of displays and find out how you might connect your monitor in future.

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