The first Xbox add-ons that purportedly allow the console to play illegally copied game software have gone on sale, but analysts say they're unlikely to inspire a Napster-like wave of copy infringement. The Xtender, a "mod chip" intended to be added to the main circuit board of the Xbox, went on sale last weekend through retailers such as Hong Kong-based Lik Sang. Three other Xbox mod chips are also in development.

Most of the mod chips promise similar functions based on disabling copy-protection features built into the Xbox. Customers are promised the ability to play games copied on recordable CD and DVD discs (and perhaps swapped as files on the Internet), play otherwise inaccessible foreign titles, and copy DVD movie discs otherwise protected by software from Macrovision. The makers of the Xtender, the Enigma and the Messiah mod chips did not respond to e-mail requests for comment. Analysts said the chips are unlikely to promote a wave of illegal file swapping similar to the MP3 phenomenon that has polarized the music industry or to the emerging movie piracy threat.