Comparison of high definition optical disc formats Blu-ray disc players since the end of the format war. Blu-ray Disc has a higher maximum disc capacity than HD DVD (50 GB vs. 30 GB for a double layered disc). In September 2007 the DVD Forum approved a preliminary specification for the triple-layer 51GB HD DVD (ROM only) disc though Toshiba never stated whether it was compatible with existing HD DVD players. In September 2006 TDK announced a prototype Blu-ray Disc with a capacity of 200GB. TDK was also the first to develop a Blu-ray prototype with a capacity of 100GB in May 2005. In October 2007 Hitachi developed
Optical disc to be used in the Library of Congress archiving efforts. The STC disks utilized a sealed cartridge with an optical window for protection . The CD-ROM format was developed by Sony and Denon, introduced in 1984, as an extension of Compact Disc Digital Audio and adapted to hold any form of digital data. The same year, Sony demonstrated a LaserDisc data storage format, with a larger data capacity of 3.28 GB. In the late 1980s and early 1990s, Optex, Inc. of Rockville, MD, built an erasable optical digital video disc system using Electron Trapping Optical Media (ETOM). Although this technology