Microsoft IE9 developer preview with HTML5 support ready for download

On March 16, Microsoft is making a first developer preview of Internet Explorer (IE) 9 available for download from www.IETestDrive.com.

The IE 9 Platform Preview doesn't include the IE 9 user interface; instead, it is the plumbing, specifically the new Microsoft JavaScript engine (which is codenamed "Chakra") and the new graphics subsystem, coupled with a home page full of test sites. There's no back button and no built-in security. It's basically the IE 9 rendering engine and early developer tools.

Microsoft officials will show off the IE 9 developer preview and discuss Microsoft's planned support for more of the emerging HTML5, CSS3 and SVG2 standards with that product during the Tuesday morning Mix 10 keynote.

"We love HTML5 so much we actually want it to work," quipped Dean Hachamovitch, the General Manager of the IE team, during a briefing I attended at Microsoft last week about IE 9.

As Microsoft supports more of the HTML5, CSS3 and SVG2 markup, the company expects its ACID3 ratings to go up, officials said. At the Professional Developers Conference in November, Microsoft officials showed a very early build of IE 9, which earned an ACID3 score of 32. The build out today is up to 55, according to company officials.

HTML5 applications are a lot richer and demanding, in terms of graphics and speed than Ajax applications. So it's logical they'll work better on multi-core machines where the browser can take advantage of multicore performance, Microsoft officials argue. That's why Microsoft's new JavaScript engine is built to take advantage of two cores, with the second core compiling JavaScript down to native machine code to help speed up the browser. (Once the native code is available, there's no need to use interpreted code on Core 1, meaning an app spends less time in JavaScript.)

Microsoft is planning to deliver a lot more preview builds of IE 9 before it hits beta. In fact, the team is committing to delivering an update every eight weeks, and to interact with developers via the Microsoft Connect feedback loop. Microsoft officials wouldn't say when to expect the first IE 9 beta or to provide any kind of ship date target for the final release. (I'm still betting Microsoft will deliver the final a few months before Windows 8 ships, in 2011 or so.)

Microsoft's high-level goals for IE 9 include making the browser snappier, maintaining compatibility with Web sites at at least the same level as IE 8 and, ultimately, enabling developers to use the same markup across IE 9 and other non-Microsoft browsers. That last of these three guiding principles is more theoretical and real at this point, but it's interesting Microsoft is thinking this way.

I'll be curious to hear what developers think of the preview once you download it.

Update: Hachamovitch said in a Q&A with press and analysts following the keynote that IE 9 will not support XP. (No big surprise there.) The preview runs on Vista SP2 and higher (which I'd figure will be the operating systems supported once IE 9 ships in final form).