Toshiba has unveiled a prototype hard-disk drive that's smaller than any currently on the market and that could start appearing in devices such as cellular telephones and digital music players before the end of this year.

The drive is the same length and width as an SD (Secure Digital) memory card and is 1 millimetre thicker, said Maciek Brzeski, vice president of marketing at Toshiba's U.S. storage media division.

A prototype on display at the Consumer Electronics Show (CES) in Las Vegas this week has a data storage capacity of 2GB and Toshiba is also planning to produce a sample drive with 4GB capacity around the middle of this year, said Brzeski.

The device itself is a miniaturised version of the kind of drive found inside a personal computer and features a recording platter, the media part of the hard-disk drive on which data is stored, that measures 0.85 inches in diameter,

Most current desktop computers use drives with a 3.5-inch diameter platter while notebook computers usually use 2.5-inch drives. Even smaller drives are used in digital music players -- Apple Computer's iPod and iPod mini use 1.8-inch and 1.0-inch drives respectively, but until now no company has unveiled a smaller device.

Getting 2GB of data onto a recording platter this small did not require any special data storage technology. The disk media has a recording density of the drive is 80G bits per square inch which is the same as that used in Toshiba's 40GB 2.5-inch hard-disk drives aimed at notebook computer use, according to Brzeski.

As the company makes advances in this technology it should enable higher capacity versions of both the 2.5-inch and 0.85-inch drives, said Brzeski. The company anticipates a 10G-byte version of the 0.85-inch drive by the end of 2005.

It has a total weight of less than 10 grams and external dimensions of 3.3 millimetres by 24 millimeters by 32 millimetres.

Despite its similarity in size to an SD memory card Toshiba says the device has been developed to be embedded into electronics devices rather than be packaged as removable media.

"As far as we are concerned it will always be an embedded device," said Brzeski. "Because of its form-factor you could make it removable."

It is expected to be used in small handheld portable devices such as cellular telephones, digital audio players, PDAs (personal digital assistants), digital still cameras and camcorders, said Brzeski. Serious talks with manufacturers of some of these devices have already begun, he said.

Toshiba, which is showing the prototype at the Consumer Electronics Show (CES) in Las Vegas this week, said it expects to begin sample production in the middle of this year and begin commercial production in late 2004.

Before sample production begins the company has to decide on what interface will be fitted on the drive.

"Because of its size it cannot support a full-blown ATAPI, Firewire or Serial ATA interface but we are evaluating two or three industry standard interfaces," said Brzeski.

He said other tasks that remain include tuning the firmware to provide the best balance between low power consumption and performance. The company wouldn't disclose prices although provide one hint.

"We haven't finalised pricing but the intent is by the end of the year for production to be between 200,000 to 300,000 (units) per month so its obviously not going to be US$500," he said. "We are aiming to get it into mass market consumer electronics such as high-end phones, GPS (Global Positioning System) receivers and MP3 players."

With the development of the 0.85-inch drive, Toshiba is also unlikely to work on development of 1-inch hard disk drives, said Brzeski.

"If you look at where consumer electronics is going, the trend is that everything is getting smaller and thinner," he said.