The supercomputer that fits into a screen just two inches thin

They used to fill entire floors of buildings and were so costly only governments or large companies could afford them.

They used to fill entire floors of buildings and were so costly only governments or large companies could afford them.

Yesterday, Apple Computer showed just how far technology has come when it unveiled the new version of its iMac computer, squeezing the machine behind a 2in-thick flat screen that appears to hover above the desktop.

The iMac G5, named for the chip powering it, will be available from the middle of this month, said Phil Schiller, Apple's head of marketing, who demonstrated the machine at a show in Paris. "With the entire system, including a 17in or 20in display, just two inches thin, a lot of people will be wondering, 'Where did the computer go?'" Mr Schiller said.

And the price has shrunk, too. Starting at £919, the new iMac is cheaper than its predecessor, which was phased out in July.

And in historical terms, it has as much processing power as a Cray-2 supercomputer of 1985, which could manage about a billion calculations per second ("gigaflops") but required a cooling tower, measured 1.3m across, and cost £6m apiece.

Apple expects that iMac G5 buyers will be the same household and small business buyers who made its blue gumdrop-shaped iMac a hit in 1997.

That turned the company's fortunes around and made its designer, the British-born Jonathan Ive, a star among his peers.

Side-on, the new iMac looks like a giant sibling to the company's iPod digital music players, floating above the desktop on a sturdy aluminium stand on which the screen can pivot. But it is also weighty: the machine weighs 18lbs (8.2kg), packing in a hard drive, up to two gigabytes of RAM, a DVD-burning drive, the power supply, and wireless networking.

But yesterday, Apple concentrated on its elegance. "If you use a wireless keyboard and mouse, you only have to plug one wire in, the power," Mr Schiller said.

* Five million tracks have been downloaded through Apple's online European iTunes music store in the 10 weeks since it opened on 15 June, the company said.