E3: Xbox 360 "backwards compatibility" explained

Following earlier indications that the Xbox 360 will only be backwards compatible with some Xbox games, Microsoft has admitted that existing software will need to be recompiled before it can be run on the new console.

The problem, it says, is down to hardware incompatibility - since the current Xbox uses an Intel processor, but the 360 will use IBM's PowerPC architecture, while NVIDIA's graphics solution is being replaced with an ATI one.

As many commentators have pointed out over the last few months, this means backwards compatibility problems. The solution Microsoft has reached is apparently to recompiled current-gen Xbox games so that they can be played on the 360. First on the list, it says, are the best-selling Halo titles.

The news has raised more questions than it answers, however, as it suggests that game titles may need to be modified somehow before players can use them on their new consoles - but Microsoft has denied that it will ask players to pay for new versions of the software.

"At launch, Xbox 360 will be backward compatible with the top Xbox games," Xbox PR manager Michael Wolf told GamesIndustry.biz today. "Our goal is to have every Xbox game work on Xbox 360. You will NOT need to purchase a new 'version' - your original games will work on Xbox 360."

Sony and Nintendo have already confirmed that their next-gen consoles - the PS3 and Revolution - will play all the games in their respective back catalogues, offering consumers a huge choice of titles at launch.