CHD's also represent optical media, not just HDD's. For example the SEGA NAOMI arcade hardware was based on the Dreamcast. As such, GD-ROM was one medium for ga

CHD's also represent optical media, not just HDD's. For example the SEGA NAOMI arcade hardware was based on the Dreamcast. As such, GD-ROM was one medium for games. the GD-ROMs are dumped as CHD's.