DVD plus R DL
DVD+R DL, also known as DVD+R9, is a derivative of the DVD+R format. Its use was first demonstrated in October 2003. The format is unique in that it uses discs with two layers of writeable polycarbonate, each capable of storing 4.7 GB of data, doubling the total disc capacity to 8.5 GB. Discs can be read in almost all DVD-ROM drives, as they were provided for in the original DVD+RW specification, but can only be created using DVD+RW DL drives.
DL drives started appearing on the market during Summer 2004, at prices comparable to those of existing single-layer drives. However, the media for these drives, at $10 to $15 per disc, is many times that of single-layer media. Current DL drives write dual layer disks at a fraction of single-layer speeds.
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