Bill Gates has admitted Microsoft's "mistakes" have left it behind on mobile phones.
In an interview with CBS the Microsoft founder and current chairman said that he wasn't satisfied with the level of innovation that the company had produced.
"There were a lot of amazing things that [CEO] Steve [Ballmer]'s leadership got done with the company in the last year. Windows 8 is key to the future, the Surface computer. Bing, people are seeing as a better search product, Xbox."
"But is is it enough?" he said in the CBS interview. "No, he and I are not satisfied that in terms of, you know, breakthrough things, that we're doing everything possible."
Gates added that Microsoft had not "[got] out in the lead early" on mobile phones, implying Windows Phone has a long way to go to catch up.
"We didn't miss cell phones, but the way that we went about it didn't allow us to get the leadership. So it's clearly a mistake."
Gates also discussed with philanthropic work, which now occupies the bulk of his time after stepping back from the day-to-day leadership of Microsoft.