Microsoft has a knack for comebacks. History suggests that the company is rarely first with a technology, but it is persistent -- and it often prevails.
The track record is lengthy: personal computer operating systems, point-and-click graphical computing, productivity software, data center software, the Internet browser and even video game consoles and software.
This week, the company is trying to begin another come-from-behind campaign -- this time, in touch-screen tablet computing, with its Windows 8 operating system. Products using the new software are not expected until next year. But the crucial effort to woo software developers to write apps for Windows 8 starts Tuesday at a four-day conference in Anaheim, Calif.
Microsoft will give away an early "preview" version of Windows 8 and thousands of tablets, made by Samsung, to developers at the conference, according to two industry consultants who have been told about the plans but would talk about them only if they were not named.
For Microsoft, the stakes are high. Its Windows business remains huge and immensely profitable, but the franchise is showing its age, with revenue and profits slipping in the year that ended in July.
"Microsoft has got to make this work," said Richard Doherty, an analyst at Envisioneering, a technology research firm.
Tablets, as well as smartphones, look to be the computing devices of the future. Sales forecasts of personal computers have been scaled back in recent months, as consumers and business people have increasingly chosen tablets.
Apple rules the tablet market with its iPad, while others have stumbled. Last month, Hewlett-Packard killed its TouchPad tablet, which used H.P.'s WebOS software. Research in Motion, maker of the BlackBerry, has struggled to find buyers for its tablet, the PlayBook. Tablets running Google's Android software have had little success so far, and ones using Microsoft's Windows 7 operating system have had even less.
"Windows 8 is Microsoft's effort to get back in the game," said Michael Silver, an analyst at Gartner, a research firm.
Microsoft has offered glimpses of Windows 8 at a few industry conferences in recent months. The new design, Microsoft executives say, represents an ambitious rethinking of the operating system, including the chips used and the user experience. Windows 8 on a PC can be ready for use in less than 10 seconds. The look of Windows 8 borrows from Windows Phone software, the company's new smartphone operating system, which was introduced last fall. It has large, tilelike icons that represent applications like e-mail or Facebook.
Windows 8 is intended to run on both ARM chips, which now power most tablets and smartphones, and Intel microprocessors.
Microsoft executives say Windows 8 has been designed so that tablet, notebook and desktop computers run equally well and share most features. For example, they speak of a "touch first" philosophy, meaning the touch features of Windows 8 work smoothly on tablets and on notebook and desktop PCs.
Taps and finger swipes on a screen, Microsoft executives say, will become a routine way to open, close and browse applications, even on machines that have keyboards. Touch screens, they suggest, could help revive excitement in the PC category.
Windows 8 also reflects Microsoft's increasing commitment to open Web standards, like HTML 5, a new technology that makes it possible for developers to write applications with rich interactive features without using proprietary software controlled by individual companies. In the past, Microsoft had followed a more closed, proprietary path.
Microsoft signaled its new approach in March with the release of Internet Explorer 9, a Web browser that was tailored for HTML 5. But the browser also includes software features that can take advantage of the underlying Windows operating system for faster performance.
The goal, Microsoft executives say, is to reduce the skills that developers will need to write applications for Windows 8, which will run smoothly on both tablets and PCs. "Windows 8 will provide a unique industry opportunity across hardware architectures for developers," said Steven Sinofsky, president of Microsoft's Windows division.
Web developers have been impressed with Microsoft's new approach. "Microsoft is opening things up for Web developers," said Emily P. Lewis, a 37-year-old Web applications designer in Albuquerque. "They had no choice. What I do isn't a Windows thing or an Apple thing."
Microsoft, analysts note, has also made tools that so its millions of loyal developers of business software will not find their skills made obsolete by Windows 8. Microsoft, they say, is betting that its traditional developer community will be a ballast in the future and not an anchor.
That approach is in contrast to Apple, which often forces developers to rewrite their applications for its new products, like the iPad, favoring innovation over stability.