Paul Allen. Photograph:( Reuters )
Allen left Microsoft in 1983 after falling out with Gates and his new lieutenant, Steve Ballmer, in December 1982, only months after being diagnosed with Hodgkin's lymphoma.
Microsoft Corp co-founder Paul Allen, the man who persuaded school-friend Bill Gates to drop out of Harvard to start what became the world's biggest software company, died on Monday at the age of 65, his family said.
Allen left Microsoft in 1983, before the company became a corporate juggernaut, following a dispute with Gates, but his share of their original partnership allowed him to spend the rest of his life and billions of dollars on yachts, art, rock music, sports teams, brain research and real estate.
Allen died from complications of non-Hodgkin's lymphoma, a type of cancer, the Allen family said in a statement.
In early October, Allen had revealed he was being treated for the non-Hodgkin's lymphoma, which he also was treated for in 2009. He had an earlier brush with Hodgkin's lymphoma, another cancer, in the early 1980s before leaving Microsoft.
Music-lover Allen had a list of high-profile friends in the entertainment business, including U2 singer Bono, but preferred to avoid the limelight at his compound on Mercer Island, across Lake Washington from Seattle, where he grew up.
Allen remained loyal to the Pacific Northwest region, directing more than $1 billion to mostly local philanthropic projects, developing Seattle's South Lake Union tech hub that Amazon.com Inc calls home and building the headquarters of his Allen Institute for Brain Science there.
Paul Gardner Allen was born in Seattle on January 21, 1953, the son of a librarian father and teacher mother. He was two years older than Gates but when they met in the computer room at the exclusive Lakeside School in Seattle in 1968, they discovered a shared passion.
Allen went on to Washington State University but dropped out in 1974 to take a job with Honeywell in Boston. While there, he pestered Gates, who was studying at nearby Harvard, to quit school and join the nascent revolution in personal computing.
Gates finally agreed and in 1975 the two jointly developed BASIC software for the Altair 8800, a clunky desktop computer that cost $400 in kit form.
The pair moved to Albuquerque, New Mexico, close to the Altair's maker, and formed a company. It was Allen's idea to call it Micro-Soft, an amalgam of microcomputer and software. The hyphen was later dropped.
Allen was in charge of Microsoft's technical operations for the company's first eight years, making him one of the handful of people who created early software such as MS-DOS and Word that enabled the PC revolution and thrust Microsoft to the top.
But he had ceased to be on the cutting edge of software development by the early 1980s. He never displayed the commercial instinct of Gates, who generally is credited with powering Microsoft's rise to ubiquity in the 1990s.
Allen left Microsoft in 1983 after falling out with Gates and his new lieutenant, Steve Ballmer, in December 1982, only months after being diagnosed with Hodgkin's lymphoma. As he recalled in his 2011 memoir "Idea Man," he overheard Gates and Ballmer secretly plotting to reduce his ownership stake.
"They were bemoaning my recent lack of production and discussing how they might dilute my Microsoft equity by issuing options to themselves and other shareholders," Allen wrote.
Gates and Ballmer later apologized but the damage was done and Allen left Microsoft, although he remained on the board until 2000.
Allen recovered from his cancer after radiation treatment but in 2009 was diagnosed with non-Hodgkin's lymphoma, another form of blood cancer. He went into remission in April 2010 but the disease resurfaced in 2018.
Allen held onto his share of the company. His 28 per cent stake at Microsoft's initial public offering in 1986 instantly made him a multi-millionaire.
His wealth peaked at about $30 billion in late 1999, according to Forbes magazine, but Allen was hurt by the sharp decline in Microsoft stock after the dot.com bubble burst in 2000 and some unprofitable technology investments.
In October 2018, Forbes magazine estimated his wealth at $21.7 billion and said he was the 44th richest person in the world.
Allen, the owner of 42 US patents, liked to cast himself as a technology visionary who drove Microsoft's early success and saw the future of connected computing long before the Internet.
Allen bought the Portland Trail Blazers basketball team in 1988 and became a local hero in 1997 when he purchased the Seattle Seahawks football franchise after the previous owner had tried to move the team to California. The Seahawks won the Super Bowl in February 2014 and both franchises are now valued at many times what Allen paid for them.
All the while, the never-married Allen pursued myriad personal projects and pastimes. He owned one of the world's biggest yachts, the 400-foot (122 meters) Octopus, which was the venue for many lavish parties and the base for scuba expeditions.
A rock 'n' roll aficionado, Allen had a band on call to jam with when he wanted and spent more than $250 million building a museum devoted to his hero, Jimi Hendrix, which morphed into a music and science fiction exhibit designed by Frank Gehry.
He spent millions more on a collection of vintage warplanes and funded the first non-government rocket to make it into space. He also collected priceless antiquities and works by Monet, Rodin and Rothko to put in his extensive art collection.
Like Gates, Allen was a dedicated philanthropist, giving away more than $1.5 billion in his lifetime and pledging to donate more than half his wealth to charity.
Through various vehicles, Allen focused his giving on brain science, motivated by the loss of his mother to Alzheimer's disease, along with universities and libraries.