Microsoft chairman Bill Gates believes that the future of computing lies in the mobility of new systems, with the mobile phone becoming a "digital wallet". 

"Historically, a phone was something you used to make phone calls," said Gates in his keynote speech at the Government Leaders Forum in Washington D.C.

"Today, the idea that your mail and calendar are there, that it just connects up to Exchange, it's secure, it's synchronised, is commonsense for all the new phone platforms.

"In the future, you'll be able to speak to your phone and have that recognition. You'll be able to use the camera on the phone not just for pictures, but to translate a sign into your language, or photograph an expense receipt and have the numbers recognised and filed away on an automatic basis.

"So it becomes a very intelligent device. The ability to be the digital wallet will be commonplace for that device in your pocket."

However, Gates, who was this week confirmed as the richest man in the world with a personal fortune of $50bn, also poured scorn on MIT's One Laptop Per Child initiative that is backed by Google. 

"The last thing you want for a shared-use computer is for it to be something without a disk, and with a tiny little screen," he said.

"If you are going to have people sharing the computer, get a broadband connection and have somebody there who can support the user."

Gates also took a pop at the wind-up system used to provide some of the MIT laptop's power. "Geez, get a decent computer where you can actually read the text and you're not sitting there cranking the thing while you're trying to type," he said.

During the speech, Gates showed off an ultra-mobile computer from Samsung that retails for $600 to $1,000.

"We've had portable computers for a long time, and they're getting smaller and faster. This improvement by the hardware vendors has made them thinner, less expensive and lighter. Just last week a number of our partners brought out what we call Ultra-Mobile PCs," he said.