DisplayPort and USB

This week, I’ve been back in the office and starting to catch up with some of the things that I should have been doing when I was away. I managed to get the IBC report done and the Munich Digital Signage conference report is nearly ready for next week – we’re waiting for some info from the organisers. We have included the report from Tom from the Midwich event that took place close to our offices in Ascot. Anyway, with these extra reports, this month has been one of the most productive for us in terms of news.

Our front page this week is about the integration of DisplayPort with USB. Interfaces between systems and displays have always been a hot topic for our newsletter and we first reported on USB when it was announced at WinHEC (Windows Hardware Engineering Conference) in March 1995. At that time, USB was seen as a way of dealing with the multiple different connectors and systems used to connect peripherals with PCs. Every kind of peripheral had its own kind of connector, cable and driver requirements. It was a nightmare.

I was selling printers back in the 1980s and early on in that job, I remember a >200km drive I made to show a big potential client a printer. I had called the dealer before. “Are you 100% sure that the printer interface is Centronics?”. “Yes”, he said. When I got there, the printer was a Centronics, but it had a serial interface, not the well known Centronics parallel interface! After that, I always took everything that I needed to do a demo, including my own PC – it was a lesson learned. But just getting an RS232 serial interface to work was a challenge – I used a “breakout box” that our technical guys had made for me and it’s still sitting in a box in my garage, I think.

USB changed all that, especially as Plug & Play became the key technology and the success of USB has been quite astonishing. There is hardly a consumer device that doesn’t use it and, even for power and charging use, it has become ubiquitous, although not widely in one of its early target markets, telephony. It’s amazing to think that the speed of USB was just 12Mbps when it was launched in 1995.

It’s hard to remember, given their relative strength now, that USB was in fierce competition with Firewire for a strong position. Firewire supporters pointed out that USB needed a lot of central processing (which suited Intel) while Firewire (P1394) was more distributed and was more of a peer-to-peer system. In the end, that turned out to be a weakness, as very low cost peripherals such as mice and keyboards could not afford the amount of processing needed for Firewire, so the sheer volume of cheap peripherals drove USB costs down and the development of the standard on.

Display interfaces, on the other hand, have been a continuing battle. From VGA, VESA tried to move to Plug & Display. Then there was VEVC and a brief foray into DFP for digital displays. Intel waded in with DVI for a while, although that initiative faded when it was too clunky for mobile systems and HDMI and DisplayPort came along. There was even an attempt by VESA to develop an alternative to VGA – the NAVI. We’ve reported on them all (and I worried that I might have missed one or two, but checking Bob Myer’s excellent 2002 Wiley book on display interfaces, I seem to have got the main ones!).

I have always been a fan of the concept of DisplayPort, and some of the features that I liked in the initial concept, such as packetisation, are only just becoming supported more widely in allowing multiscreens. The combination of DisplayPort and USB may be a difficult one for HDMI, which we have thought has been in a somewhat defensive position since the launch of HDMI20 at IFA 2013.