As the world's largest high-tech fair, the CeBIT, opens in the German city of Hanover, Gates wrote in an article for the mass-selling Bild tabloid that computer use would become as routine as switching on a light.

"Up to now the computer industry has produced and sold a billion personal computers worldwide. Add to that another billion by 2010," he wrote, in words translated into German.

The first billion were standard computers, with a screen, mouse, keyboard and hard drive, he added.

But the second billion would be radically different: computers capable of meeting their electricity needs literally out of thin air, with huge memories and flat or foldable screens yet able to provide a complete hi-fi, Internet, cinema, business and personal use system.

"Using computers will become so simple and everyday that we'll hardly even notice we're doing it any more," added the world's richest man, who has built his fortune on developing and selling computer technology.

SPACE.WIRE