HD DVD Quick Facts - HD DVD Format's Various ROM Configurations for Pre-packaged Content

HD DVD-ROM (Read Only) currently comes in 4 configurations.

>> HD-15 refers to Single-Sided, Single-Layer disc with a total capacity of 15GB.
>> HD-30 refers to Single-Sided, Dual-Layer disc with a total capacity of 30GB.
>> HD-30D* refers to Double-Sided, Single-Layer disc with total capacity of 30GB.
>> HD-60D* refers to Double-Sided, Dual-Layer disc with a total capacity of 60GB.

A fifth and sixth configuration, the HD DVD-ROM (51G) is currently undergoing the standardisation process and its preliminary physical specifications been approved by the DVD Forum in September 2007. The standardisation process for the 51G disc is expected to be completed by December 2007.

>> HD DVD-ROM (51G) refers to Single-Sided, Triple-Layer disc with a total capacity of 51GB.

* These may not be the official naming convention. Their use here is just to simplify and differentiate.

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HD DVD / DVD Twin Format Disc refers to the Single-Sided, Dual-Layer disc with one layer of HD DVD [HD-15 (15GB HD)] and one layer of DVD [DVD-5 (4.7GB SD)].

Another variation of the Twin Format Disc that has been approved is the Single-Sided, Triple-Layer disc with two layers of HD DVD [HD-30 (30GB HD)] and one layer of DVD [DVD-5 (4.7GB SD)].

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HD DVD / SD DVD Combo Format Disc Configurations:

>> HD DVD / SD DVD Combo Format discs are Double-Sided, with HD DVD and SD DVD (or just simply DVD) on flip sides.

>> Combination-1: HD-15 (15GB HD) + DVD-5 (4.7GB SD)

>> Combination-2: HD-15 (15GB HD) + DVD-9 (8.5GB SD)

>> Combination-3: HD-30 (30GB HD) + DVD-5 (4.7GB SD)

>> Combination-4: HD-30 (30GB HD) + DVD-9 (8.5GB SD)

The DVD layers/sides of both the Twin Format and Combo Format discs are suppose to be fully functional on standard DVD players although there may be some compatibility issues with a few DVD players.