ISO 9660 Data Format for CDs, CD-ROMs, CD-Rs and CD-RWs

ISO 9660 is a data format designed by the International Standards Organisation in 1984. It’s the accepted cross-platform protocol for filenames and directory structures. Filenames are restricted to uppercase letters, the digits 0 to 9 and the underscore character, _. Nothing else is allowed. Directory names can be a maximum of only eight characters (with no extension) and can only be eight sub-directories deep. The standard can be ignored under Windows 95 – but older CD-ROM drives may not be able to handle the resulting non-standard discs. Every CD has a table of contents (TOC) which carries track information. Orange Book solves the problems of writing CDs, where subsequent recording sessions on the same disc require their own update TOC. Part of the appeal of Kodak’s Photo-CD format is that its not necessary to fill the disc with images on the first go: more images can be added at later until the disc is full. The information on a Photo-CD is Yellow Book CD-ROM format and consequently readable on any multi-session compatible drive. However, the ISO 9660 file format used by CD and CD-R discs and the original disc or session-at-a-time standards didn’t lend themselves to adding data in small increments. Writing multiple sessions to a disc results in about 13Mb of disc space being wasted for every session, and the original standard limits the number of tracks that can be put on a disc to 99. These limitations were subsequently addressed by the OSTA’s (Optical Storage Technology Association) ISO 13346 Universal Disc Format (UDF) standard. This operating-system independent standard for storing data on optical media, including CD-R, CD-RW...

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