Microsoft co-founder Paul Allen, who visualized the indispensability of the personal computer more than 40 years ago, died Monday at 65.
Allen's family said he died in Seattle of non-Hodgkin's lymphoma, a form of cancer he had been battling off and on since 2009.
After persuading high school friend Bill Gates to drop out of Harvard in 1975, the two teamed up to develop a rudimentary software that hobbyists used to operate home-built computers.
"I expect the personal computer to become the kind of thing that people carry with them, a companion that takes notes, does accounting, gives reminders, handles a thousand personal tasks," Allen wrote in Personal Computing magazine in 1977.
Allen and Gates called their company Microsoft and spent the next several years developing the software that revolutionized the world.
Allen and Gates split in 1983, but Allen kept his share of Microsoft, making him a billionaire.
Gates issued a statement on Allen's death late Monday.
"I am heartbroken by the passing of one of my oldest and dearest friends, Paul Allen," he said.
According to Forbes magazine, Allen was worth nearly $22 billion at the time of his death, making him the world's 44th wealthiest person.
Allen was also owner of the National Football League's Seattle Seahawks, and the Portland Trail Blazers professional basketball team.
He also used his wealth to refurbish a crumbling neighborhood of his native Seattle, turning it into a headquarters for Amazon.