Google gave the first public look at its Chrome OS four months after declaring its intention of developing the PC’s main software, a move that pits it directly against Microsoft Corp and Apple Inc.

True to Google’s Internet-pedigree, the Chrome OS resembles a Web browser more than it does a traditional computer operating system like Microsoft Windows, matching Google’s ambition to drive people to the Web — where they can see Google ads. Google said the software will initially be available by the holiday season of 2010 on low-cost netbooks that meet Google’s hardware specifications, such as using only memory chips to store data instead of slower hard drives, the current standard.