Wozniak praises Apple's formula for success

Apple's co-founder Steve Wozniak believes one of the secrets of the company's success is that it found the formula to remain nimble and innovative despite its size.

That cannot, perhaps, be said of Microsoft, which has relied on markets and products it built up a long time ago, he says.

Nevertheless, Apple has a fight on its hands with companies such as Samsung, he tells the BBC's Chief business correspondent Linda Yueh.