We got a malaria initiative, really a phenomenal time, even though in the early stages there was some uncertainty. Then of course [Barack] Obama, although he had budget constraints, he believed in these things; a lot of new initiatives, including in agriculture.

When you have a fortune that is almost hard to imagine, the best thing is not to pass that on to one's children. That distorts their life situation.

Digital technology has several features that can make it much easier for teachers to pay special attention to all their students.

When you write a piece of software you assume a certain type of hardware. If you assume hardware that's too powerful then you can't sell many copies cause very few people have that machine. If you assume hardware that's too simple your product can't do as much.

So we do software for watches, for phones, for TV sets, for cars. And some of these take a long time to catch on.

We're responsible for the creation of the PC industry. The whole idea of compatible machines and lots of software - that's something we brought to computing. And so it's a responsibility for us to make sure that things like security don't get in the way of that dream.

'I don't know' has become 'I don't know yet'.