Timeline: The Gates era at Microsoft

Bill Gates is pretty much synonymous with Microsoft Corp., which he co-founded and built into the world's largest software vendor and the IT industry's most influential company. But Gates is stepping away from his day-to-day role at Microsoft at the end of this month. Here's a brief history of his 33 years at the company.

1975: Bill Gates, then 19, and 22-year-old boyhood friend Paul Allen found "Micro-Soft" in Albuquerque, initially to create a version of the BASIC programming language for the Altair 8800 personal computer. The formation of the new business continues a partnership from their school days in Seattle that several years earlier had produced a computerized traffic-counting machine called Traf-O-Data, which was based on the Intel 8008 microprocessor. Gates and Allen later drop the hyphen, then move Microsoft to the Seattle area in 1979 and officially incorporate it in 1981.

1976: Gates writes his famous "Open Letter to Hobbyists," accusing them of pirating Micro-Soft's Altair BASIC. "As the majority of hobbyists must be aware, most of you steal your software," he writes. The letter concludes: "Nothing would please me more than being able to hire ten programmers and deluge the hobby market with good software."

1981: IBM introduces its first PC, an 8088-based system running Microsoft's 16-bit MS-DOS 1.0 operating system. Microsoft didn't develop the software itself; it bought the rights to the technology from a company called Seattle Computer Products, which originally marketed the operating system under the name QDOS (for "Quick and Dirty Operating System").

1983: Microsoft announces Windows, initially as an extension of MS-DOS giving the software a graphical operating environment. But starting something of a tradition, Windows wouldn't be ready to ship until...

1985: The company finally releases Windows 1.0, two years and 10 days after the initial announcement. Gates initially wanted to call the product Interface Manager but was talked out of it. Even Microsoft acknowledges that neither Windows 1.0 nor Windows 2.0, which followed in 1987, really set the world on fire. But they did get the attention of executives at what was then called Apple Computer Inc., who noticed some similarities between Windows and Apple's operating systems. (See some screen grabs of Windows 2.0).

1988: Apple files Apple Computer Inc. v. Microsoft Corporation, a copyright infringement lawsuit aimed at stopping Microsoft, as well as Hewlett-Packard Co., from using graphical user interface features that Apple claimed were copied from its Lisa and Macintosh operating systems. A federal judge threw out most of the claims four years later. But the lawsuit was a harbinger of things to come for Microsoft.

1989: Microsoft introduces the initial version of its Office application suite — ironically for the Macintosh, with a Windows version not following until the next year. Office still dominates the desktop apps market today, but online rivals such as Google Docs and free office suites such as the one from OpenOffice.org are starting to pose some threats to its hegemony.

1990: Microsoft launches Windows 3.0 and goes on to sell 10 million copies of it within two years, establishing Windows as the dominant PC operating system. This was also the year when the development deal between Microsoft and IBM for the OS/2 operating system fell apart — big surprise, considering the sudden success of Windows 3.0. Just three years earlier, Microsoft had announced OS/2 as its planned successor to DOS and Windows.

1994: Gates becomes the wealthiest person in America, according to Forbes magazine, which a year later proclaims him the richest individual in the world. Gates retained both of those distinctions until this year, when he lost them to one of his friends, investor Warren Buffett. But Forbes said that Gates' net worth still increased $2 billion over the magazine's 2007 estimate, to a total of $58 billion as of Feb. 11.

1995: Microsoft misses the first stop of the Internet Express (see part 1 and part 2 of this BusinessWeek story). Trying to jump aboard the fast-moving online train, Gates writes a "let's get going" internal memo (download PDF) that is titled "The Internet Tidal Wave" and proclaims that the Net "is the single most important development to come along since the IBM PC." Microsoft quickly launches Internet Explorer, using Mosaic Web browser technology licensed from Spyglass Inc.

Also in 1995, Microsoft with great fanfare releases Windows 95, code-named Chicago — using the Rolling Stones song "Start Me Up" as the centerpiece of its marketing campaign for the operating system, which added the Start button to Windows. While not exclusively 32-bit, the new operating system marked a shift to PCs based on Intel's 32-bit 80386 chip, although Gates apparently wasn't impressed by that processor at first. Windows 95 also sounded the death knell for OS/2, although IBM continued to update and market that operating system until 2005.