Hitachi Ltd has taken the Toshiba Corp standard for super-high-capacity digital video disks – that’s the two-sided one rather than the two layer one – and is claiming a breakthrough by successfully adding a second layer to each side, so that the thing can store 18Gb in total, which it says is enough to play back over two hours of high definition video – typically movies, but it also sees it being used for music, films and text. The disk is the same size as the standard 4.7 Compact Disk, and although it is 1.2mm thick, it is not backwards-compatible with current CD-ROM drives. Hitachi had help with the thing from its affiliate Nippon Columbia Co. Hitachi plans to start marketing its disk, the SD-18, as well as players for it, in the latter half of 1997.
