Microsoft chairman Bill Gates has spoken out about his dissatisfaction with the pace of innovation at the company he founded in the 1970s.
Gates handed over the role of CEO to Steve Ballmer in January 2000 and has been blamed for a number of mis-steps over the past 12 years, from Windows Mobile and Windows Vista to Windows 8 RT.
In a rare interview with CBS Television in the US, Gates talked about Microsoft's current malaise, with it facing criticism for the confusion caused by the plethora of 8-series operating systems - Windows 8, Windows 8 RT and Windows Phone 8 - as well as the business mind that he has brought to his charity work via the Bill & Melinda Gates Foundation.
In response to the question, "are you happy with his [Ballmer's] performance", Bill Gates responded: "He and I are two of the most self-critical people I know. There are a lot of amazing things that Steve's leadership achieved. Windows 8, the Surface computer, Bing, Xbox. Is it enough? No. He and I are not satisfied."
For example, someone with an Xbox console, Windows 8 PC and Windows Phone 8 will have a completely different experience - almost as if they were developed by different companies.
The Bing search engine, meanwhile, has just single-digit market share, while Ballmer passed the opportunity to buy Yahoo over the past decade, while spending $6.4bn (£4.13bn) on advertising platform aQuantive, later written down by $6.2bn (£4bn), and the $8.5bn (£5.5bn) acquisition of Skype, for which Microsoft arguably overpaid.
He continued: "There's a lot of things like cell phones where we didn't get out in the lead very early... we didn't miss cell phones, but the way we went about it didn't allow us to get leadership."
In his "charity" work, Gates says that he is keen to push better science learning in schools and innovation, especially in energy "whether that's a new nuclear reactor or cheap solar".