Hybrid disc

A hybrid disc is a disc, such as CD-ROM or Blu-ray Disc, which contains multiple types of data which can be used differently on different devices. These include CD-ROM music albums containing video files viewable on a personal computer, or feature film Blu-ray Discs containing interactive content when used with a PlayStation 3 games console.

A hybrid disc is a CD-ROM that has multiple file systems, so that it can be used on various system software, for example both Apple Macintosh and Microsoft Windows based operating systems.

A hybrid disc has multiple file systems installed on it, typically ISO 9660 and HFS+ (or HFS on older discs). The reason for the format is primarily that ISO 9660 has severe restrictions placed on filenames (initially only 8 characters per file, and a depths of 8 directories, similar to the Microsoft FAT filesystem) and lacks key structures present in Apple Computer's HFS and HFS+ file systems. Another key factor is that ISO 9660 does not support resource forks, which is critical to the classic Mac OS' software design (macOS has removed much of the emphasis/need for resource forks in application design). Companies that released products for both DOS (later Windows) and the classic Mac OS (later macOS) could release a CD containing software for both, natively readable on either system. Data files can even be shared by both partitions, while keeping the platform specific data separate. In a true (or shared) hybrid HFS filesystem, files common to both the ISO 9660 and HFS partitions are stored only once, with the ISO 9660 partition pointing to file content in the HFS area (or vice versa). Blizzard Entertainment has released most of their computer games on hybrid CDs. By default, Mac OS 9 and macOS burn hybrid discs.

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