Some key dates in the history of Microsoft Corp.:

1975 — Paul Allen and Bill Gates, childhood friends who had co-written a programming language for the Altair hobby-kit personal computer, license it to the makers of the Altair. This programming language is the first Microsoft product.

Jan. 1, 1979 — Microsoft moves from Albuquerque, N.M., to the Seattle area.

1980 — Microsoft chosen by IBM to create operating system for its first PC. Microsoft buys the software for $50,000 from another company and renames it MS-DOS. Steve Ballmer, a classmate of Gates at Harvard, joins Microsoft.

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Aug. 12, 1981 — IBM introduces the PC, running on MS-DOS.

1983 — Microsoft introduces its Word word-processing program, announces plans to create Windows operating system. Allen resigns as vice president after being diagnosed with Hodgkin's disease, but remains on the board of directors.

November 1985 — Microsoft ships its first version of Windows.

March 13, 1986 — Microsoft's stock goes public.

Aug. 1, 1989 — Microsoft introduces earliest version of the Office business-software suite.

1991 — Federal Trade Commission investigates claims Microsoft monopolizes the market for PC operating systems. Investigation closes two years later without a formal complaint.

January 1, 1994 — Bill Gates marries Microsoft executive Melinda French on the Hawaiian island of Lanai.

July 1994 — U.S. and European antitrust investigations settled; Microsoft agrees to change contracts with PC makers. Settlement is rejected in federal court, then reinstated in 1995.

Aug. 24, 1995 — Microsoft launches Windows 95.

Nov. 27, 1995 — Microsoft releases Internet Explorer 2.0, challenging Netscape's Navigator Web browser.

Dec. 7, 1995 — Gates details shift in Microsoft strategy to focus on the Internet.

Aug. 6, 1997 — Less than a month after Gates' contemporary and rival Steve Jobs is reinstated as Apple Computer CEO, Microsoft and Apple agree to share technology and set aside long-standing feud.

Oct. 20, 1997 — Justice Department sues Microsoft, says it violated the 1994 consent decree by requiring computer makers to use its Internet browser as a condition of using Windows.

May 18, 1998 — Justice Department and 20 states sue Microsoft, alleging it illegally thwarted competition. One state later drops out of the suit.

July 21, 1998 — Ballmer becomes president of Microsoft.

Oct. 19, 1998 — The antitrust trial begins, continues into summer of 1999.

Nov. 5, 1999 — U.S. District Judge Thomas Penfield Jackson releases his findings of fact, which label Microsoft a monopoly.

Jan. 13, 2000 — Gates steps aside as CEO, giving the post to Ballmer, but remains chairman and takes position of chief software architect.

Feb. 17, 2000 — Microsoft launches Windows 2000.

June 7, 2000 — Jackson orders the breakup of Microsoft into two companies.

Sept. 26, 2000 — Supreme Court refuses to hear Microsoft's appeal of Jackson's decision, sending the case to a federal appeals court.

Sept. 6, 2001 — Justice Department says it will no longer seek a breakup of Microsoft.

Oct. 25, 2001 — Worldwide launch of Windows XP.

November 2001 — Microsoft, Justice Department reach tentative deal to settle antitrust case.

Nov. 15, 2001 — Microsoft launches Xbox home-gaming console in North America.

August 2002 — Microsoft unveils business and product changes to comply with Justice Department settlement.

June 23, 2003 — Microsoft announces Windows Mobile for handheld computers and phones.

March 24, 2004 — European Commission fines Microsoft a record $613 million for antitrust violations, though the sanction is later suspended while Microsoft appeals.

April 2, 2004 — Sun settles antitrust claims with Microsoft for $1.95 billion.

June 30, 2004 — U.S. appeals court unanimously approves settlement with Justice Department.

Dec. 22, 2004 — An EU court rejects Microsoft's appeal of the March order.

May 12, 2005 — Microsoft shows off new Xbox 360; console hits shelves in November.

July 1, 2005 — Microsoft agrees to pay IBM $775 million in cash and $75 million in software to settle antitrust claims.

Oct. 11, 2005 — RealNetworks settles antitrust claims with Microsoft for $761 million.

March 23, 2006 — Microsoft announces a shake-up in its Windows unit, two days after saying it won't have its next consumer version of Windows ready for the holiday season as planned.

June 15, 2006 — Bill Gates announces plans to withdraw from day-to-day duties at Microsoft in July 2008 so he can focus on his charitable foundation.

Nov. 14, 2006 — Microsoft introduces Zune music player.

Jan. 30, 2007 — Microsoft releases long-delayed Windows Vista and Office 2007.

Jan. 31, 2008 — Microsoft makes unsolicited offer to buy Yahoo for $44.6 billion. Eventually walks away after Yahoo won't agree to even higher offer, $47.5 billion.

June 27, 2008 — Gates steps down from full-time role in company, remains board chairman.