By Peter Svensson
The Associated Press

NEW YORK - If you just bought a DVD-burning drive for your computer and think that for once you're current with the latest and greatest, it's disappointment time.

Manufacturers are soon launching drives that can store double the amount of data on a disc.

Sony Electronics says it will be shipping drives in about two months that accept blank DVDs with two data layers. Philips Electronics will start selling a similar drive in Europe in April but is not saying when it will be available in the United States.

The write-once discs can store up to 8.5 gigabytes of data, or about four hours of DVD-quality movies, twice the capacity of regular blank DVDs. This means capacities for computer-burned DVDs are catching up with prerecorded movie DVDs, many of which are already dual-layer.

The new technology is sure to appeal to those who back up or copy movie DVDs, because they often have to reduce image quality or remove special features to fit a copied movie onto a single-layer disc. With a dual-layer drive, an exact copy on a single disc should be possible.

(The software used to copy encrypted movie DVDs is illegal in the United States, according to recent court rulings.)

The two layers of the new discs are accessed from the same side - there is no need to flip the disc to record to the second layer. Instead, a laser beam shines through the first layer to record on the second.

Sony will sell an internal drive for $230 and an external one for $330. They will be marketed only for Windows PCs, but the external one should work on Macintosh computers with the proper third-party software.

Philips will sell two internal drives with somewhat different features, both for PCs. U.S. prices have not been set.

The drives will be able to burn regular write-once and rewritable DVDs and CDs as well.

The Sony and Philips drives will use somewhat different discs. Sony calls its variant DVD-R DL. The Philips equivalent is DVD+R DL. Both disc types should be readable in standard DVD drives and players.

Sony estimates the blank discs will cost $5 to $6. Philips does not have an estimate yet.

The dual-layer discs will be slower to burn than single-layer discs - the drives will be rated as burning at 2.4 times faster than playback speed, versus eight times for single-layer discs.

A full 8.5 gigabytes will take about 45 minutes to burn.