The history of the personal computer is inextricably linked to the life story of Bill Gates - the boy from Seattle who had the audacious vision of "a computer on every desk and in every home".
EARLY INTEREST IN COMPUTERS
Allen and Gates were fascinated by early computers
28 October 1955
Bill Gates is born to a wealthy Seattle family. He is the second child of William H Gates II, an attorney, and Mary Gates, a leading charity volunteer.
Gates starts at Lakeside, an exclusive private school. He is two years junior to fellow student Paul Allen.
The Lakeside Mothers' Club buys the school a Teletype machine - a special typewriter that can send electronic messages down a phone line to a primitive computer at the local university.
Gates and Allen develop a passion for the machine and frequently sneak into the school at night to write programmes on it.
Gates uses the Teletype machine to devise the Lakeside School timetable. It is a complicated job but Gates ensures the girls he finds most attractive are scheduled to be in his classes.
The 1970s saw a leap forward in computing
Gates graduates from Lakeside and starts at Harvard. His primary subject is "Pre-Law" but he also takes classes in Mathematics and Economics. He becomes friends with a student living along the hall called Steve Ballmer.
An article appears in Popular Electronics magazine about an exciting new "personal computer", the Altair 8800, which has been developed by a company called MITS.
It uses the Intel 8080 microprocessor, making it the world's first mass-produced microcomputer. MITS is inviting readers to develop a programming language for it.
Gates and his old school friend Allen call MITS and claim to have developed a BASIC language interpreter that will work with the Altair. MITS agrees to see it. Gates and Allen work night and day to get the programme ready in time.
Some two-and-a-half thousand miles away in Silicon Valley, California, a loose association of computer "hobbyists", called the Homebrew Computer Club, is also taking an interest in the Altair. Among its number are Stephen Wozniak and Steve Jobs.
Allen travels to Albuquerque in New Mexico where MITS is based and successfully demonstrates the version of the programming language BASIC that he and Gates have developed. MITS is delighted and makes Allen vice-president and director of software.
Gates' future success was tied to his Microsoft company
Summer 1975 - Spring 1976
Gates joins Allen in Albuquerque, developing BASIC for the Altair. During this time, they start to refer to their own venture as Micro Soft or Micro-Soft.
Gates' "Open Letter to Hobbyists" is published in the Homebrew Computer Club newsletter. He makes the radical demand that computer enthusiasts respect the copyright of software developers.
Gates returns to Harvard to resume his studies.
1 April 1976
Steve Jobs and Stephen Wozniak, who have formed Apple Computer, launch their first product - the Apple I personal computer.
26 November 1976
Gates and Allen register the trademark "Microsoft". Their work has become independent of MITS. Gates has given up his Harvard studies altogether, and he and Allen are taking on staff.
Microsoft's revenues exceed $1m.
1 January 1979
Gates and Allen move Microsoft from Albuquerque to their home state of Washington. They open offices in Bellevue, a few miles from where they grew up.
11 June 1980
Gates hires his old Harvard friend Steve Ballmer as the company's first business manager.
Gates took just over half the company and his pal Allen just under a third
Summer and Autumn 1980
Gates agrees to produce the operating system for the personal computer being developed by IBM, the world's leading computer company. Crucially, Microsoft retains the right to license the operating system (MS-DOS) to other computer manufacturers.
1 July 1981
Microsoft is incorporated. Gates gets 53% of the company; Allen 31% and Ballmer 8%. The initial stock price is 95 cents.
Microsoft's revenues reach $16m. The company employs 128 people.
Allen is diagnosed with Hodgkin's Disease. Although his treatment is successful, he never returns to full-time work at Microsoft.
Microsoft's revenue reaches $140m. The company employs 910 staff.
Harvard friends Gates and Ballmer have worked together for 28 years
20 November 1985
Microsoft releases a graphical extension to its MS-DOS operating system. This is the first retail version of Windows.
Microsoft moves to Redmond, a leafy suburb of Seattle. This is where the company's headquarters have been located ever since.
13 March 1986
Microsoft goes public. On the first day of trading, the share price rises from $21 to $28.
A young Texan called Melinda French joins Microsoft as a marketing manager. She and Gates start dating.
18 March 1988
Apple files a lawsuit against Microsoft, claiming that the "look and feel" of Windows is too similar to the Apple "graphical user interface". The legal battle is to last six years and Apple eventually loses.
Microsoft Office is released.
22 May 1990
Windows 3.0 is launched and sells 100 000 copies in two weeks. Microsoft had also been working with IBM on a similar product - called OS/2.
20 August 1990
Microsoft executives attending a special meeting at the Shumway Mansion decide to abandon OS/2 and focus on Windows 3.0. Headlines later declare that Microsoft and IBM had "divorced".
RIVALS HIT BACK
Gates faced tough commercial and legal challenges as his wealth soared
Some of Microsoft's competitors start to meet to share concerns about the increasing dominance of Gates' company.
Forbes declares Gates to be the richest man in America, worth $6.3bn.
20 January 1993
Microsoft's market value overtakes that of computer giant IBM.
5 February 1993
The Federal Trade Commission is deadlocked when it meets to rule on whether Microsoft has broken anti-trust rules. The matter is referred to the Justice Department in August.
20 March 1993
On his way back from Palm Springs with Melinda French, Gates diverts their private plane to Omaha. Gates' friend, billionaire Warren Buffet, takes them to a jewellery shop he owns. Gates buys French an engagement ring.
1 January 1994
Gates marries Melinda French.
9 June 1994
Gates' mother, Mary, dies of cancer at the age of 64.
14 October 1994
The company Netscape offers its Mosaic Navigator as a free download on the internet.
Spoof stories start circulating that Microsoft has plans to buy the Catholic Church. Microsoft issues a press release denying the story.
5 July 1995
Forbes declares Gates the richest man in the world, a position he holds continuously until 2008.
26 May 1995
Gates reveals the future direction in which he wants to take Microsoft. In his "Internet Tidal Wave" memo to senior staff, he says: "I now assign the internet the highest level of importance."
24 August 1995
With a lavish publicity drive, Windows 95 and Microsoft's online service MSN are launched.
Gates takes his second proper holiday in 20 years when he travels to China with his family and close friends.
With seven million copies of Windows 95 already sold, Microsoft's profits climb by 58% in a year.
7 December 1995
Gates announces Microsoft's internet strategy to the world's press. In his controversial "Pearl Harbor" speech, he reveals plans for Microsoft's own internet browser - Explorer.
Microsoft releases Internet Explorer 3.0.
Netscape asks the Department of Justice to investigate Microsoft's discount to computer manufacturers that install Internet Explorer 3.0.
The Department of Justice and the Attorneys General of 20 states sue Microsoft for illegally thwarting competition.
25 June 1998
Microsoft launches Windows 98.
Gates urged Microsoft to ride the internet 'tidal wave' of the 1990s
Gates spends three days giving his deposition by video to the Department of Justice inquiry.
Google is incorporated by founders Larry Page and Sergey Brin
Ballmer is appointed chief executive of Microsoft. He and Gates later acknowledge that they both had a difficult time adjusting to their new roles.
7 June 2000
Following the Department of Justice inquiry, Judge Jackson rules that Microsoft should be split into two units: one to produce operating systems, the other to make other software components. He calls Microsoft an "abusive monopoly".
Microsoft's revenues reach $229bn. The dot-com crash does not affect it as badly as many other companies in the sector. The company's headcount climbs to over 39,000.
Bill Gates combined charitable work with continuing to develop Microsoft
The Gates family launches the Bill and Melinda Gates Foundation, a charitable organisation intended to "reduce inequalities in the United States and around the world". They donate billions of dollars of their own money, and it soon becomes the world's biggest philanthropic organisation.
The Court of Appeal overturns Judge Jackson's order to break up Microsoft into two corporations. However, it upholds his ruling that Microsoft illegally used licensing agreements with internet service providers and PC manufacturers to freeze out the Netscape internet browser.
25 October 2001
Microsoft launches Windows XP.
15 November 2001
Microsoft branches out into the gaming console market with its high-profile launch of the Xbox. This product is a direct competitor to Sony's PlayStation 2 and Nintendo's GameCube.
The European Commission brings anti-trust action against Microsoft.
Google's flotation paves the way for a dramatic acceleration in the company's growth: two months later it overtakes Yahoo!'s market capitalisation with a value of $50bn.
The Gates' endowments to the Bill and Melinda Gates Foundation reach almost $29bn.
In 2008 Gates finally withdrew from the Microsoft front line
15 June 2006
Gates announces that he will step back from Microsoft in two years to concentrate on his philanthropic endeavours. He reveals he has a carefully thought-through "transition" period planned and that he hopes to remain chairman of the company for life.
Windows Vista and Office 2007 are launched.
7 June 2007
Gates returns to Harvard to collect an Honorary degree.
1 Feb 2008
Microsoft makes a bid of $44.6bn for search engine company Yahoo!. For the first time in its history, Microsoft plans to borrow some of the necessary funds. Yahoo! rejects the bid.
27 February 2008
Microsoft is fined a record 899m euros by the European Commission because of the company's failure to comply with earlier anti-trust rulings. Microsoft is appealing against the fine.
The Microsoft headcount is now almost 90,000 worldwide.
27 June 2008
Gates is leaving his full-time role at Microsoft to concentrate on the work of the Bill and Melinda Gates Foundation.