"The operating systems that browsers run on were designed in an era where there was no web. So today, we're announcing a new project that's a natural extension of Google Chrome—the Google Chrome Operating System. It's our attempt to re-think what operating systems should be."

With those words, Google late last night launched a direct assault on rival Microsoft, announcing the development of its own personal-computer operating system, connected to its Chrome Web browser, which was launched late last year.

The open-source Chrome OS will first run on netbooks, "laptop-lite" portables that have been selling like hotcakes in recent months. The first netbooks running Chrome OS will be available in the second half of 2010, according to the Google statement signed by Google VP of Product Management Sundar Pichai and Engineering Director Linus Upson.

They promised "speed, simplicity and security" for the OS:

We're designing the OS to be fast and lightweight, to start up and get you onto the web in a few seconds. The user interface is minimal to stay out of your way, and most of the user experience takes place on the web. And ... we are going back to the basics and completely redesigning the underlying security architecture of the OS so that users don't have to deal with viruses, malware and security updates. It should just work.

"The move is likely to sharpen the already intense competition between Google and Microsoft, whose Windows operating system controls the basic functions of the vast majority of personal computers," writes the New York Times.

Google's OS vision is in line with its Web-based view of computing, with applications available via the Internet and being used online rather than residing within PCs—a worldview that challenges the Microsoft computing ecosystem, the Times points out.

Google apparently made the announcement a day before originally scheduled, after Ars Technica and the New York Times reported the news late Tuesday.