dual-layer ROM HD-DVD and DVD disc

I recall this was the promise of SA-CD - and look how that turned out ... i.e., the studios didn't bother to make dual layer discs.

News Stories - The IEE: "Memory-Tech and Toshiba have jointly developed a dual-layer ROM (read-only) disc that can store content in both the HD-DVD and DVD formats.

...

The new disc makes it possible for consumers to view DVD content on standard DVD players and, after purchasing an HD-DVD player, to enjoy high definition content on the HD-DVD layer from the same disc. "