The lawsuit, which seeks class action status, was filed earlier this week in Los Angeles Superior Court against Apple Computer, Dell, Gateway, HP, IBM, Sharp, Sony and Toshiba.

The lawsuit brought by Los Angeles residents Lanchau Dan, Adam Selkowitz, Tim Swan and John Zahabian centres around the way that computer hard drives are described by manufacturers.

Representatives of the eight defendants were not immediately available to comment.

According to the lawsuit, computer hard drive capacities are described in promotional material in decimal notation, but the computer reads and writes data to the drives in a binary system.

The result is that a hard drive described as being 20GB would actually have only 18.6GB of readable capacity, the lawsuit said.

The plaintiffs said this difference in convention is deceptive and leaves buyers with less storage than they thought they were getting when they purchased their computers.

For example, when a consumer buys what he thinks is a 150GB hard drive, the plaintiffs said, he actually gets only 140GB of storage space. That missing 10GB, they claim, could store an extra 2 000 digitised songs or 20 000 pictures.

The lawsuit asks for an injunction against the purportedly unfair marketing practices, an order requiring the defendants to disclose their practices to the public, restitution, disgorgement of ill-gotten profits and attorneys' fees.