Reuters is reporting that Bill Gates said a "teary" goodbye to Microsoft on his last day as boss of arguably the world's most powerful software company.

Gates has now left his "day job" at Microsoft, which he co-founded with childhood friend Paul Allen in 1975, at age 17, to concentrate on charitable efforts, although he will remain at the company as chairman.

At an employee event at Microsoft's headquarters in Redmond, Gates was joined on stage by chief exec Steve Ballmer to give a speech and answer questions.

"There won't be a day in my life when I won't be thinking about Microsoft, the great things that we're doing and wanting to help", said Gates, who "wiped away tears" as he got a standing ovation.

Ballmer, no stranger to emotional outbursts said, "There's no way to say thanks to Bill. Bill's the founder. Bill's the leader. This is Bill's baby", as he recounted how Gates persuaded him to stay on at the firm in a moment of doubt by promising: "We are going to put a computer on every desk and in every home".