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ISO 9660

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This is an old revision of this page, as edited by Tempel (talk | contribs) at 12:02, 7 June 2002 (ISO 9660 is a standard for files are stored on CD-ROMs for data exchange). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

ISO 9660, a standard published by the International Organization for Standardization, defines a file system for CD-ROM media. It aims at supporting different computer operating systems such as Microsoft Windows, Mac OS, and systems that follow the UNIX specification, so that data may be exchanged.

Levels and restrictions

There are different levels to this standard. The first level restricts file names to 8 characters with a 3 character extension.

The second level allows up to 32(?) characters in a name.

The third level allows files to be fragmented (used on CD-Rs written by the software "Direct CD" for Windows, for example).

All levels restrict names to upper case letters and underscores ("_"). Some CD mastering applications allow the user to use almost any ASCII character. While this is not compliant with the ISO 9660 standard, most CD-ROM reading operating systems, or more precisely, their ISO 9660 file systems, allow the use of those "illegal" characters, though.

Disk image appearance

Disk images of ISO 9660 file systems often have the extension .iso, but not necessarily.

Extensions

There are extensions to ISO 9660 to deal with the limitations. The most common ones are Rock Ridge and Joliet:

(Rock Ridge supports the preservation of Unix permissions and longer ASCII coded names, while Joliet supports names stored in Unicode, thus allowing almost any character to be used, even from non-roman scripts.)

Most operating systems support reading of ISO 9660 formatted discs, but only a few support the extensions such as Rock Ridge and Joliet. Operating systems that do not support the extensions will usually show the basic (non-extended) features of a plain ISO 9660 disc.

Here are some operating systems and their support for ISO 9660 and extensions:

  • Windows 95 and later: can read ISO 9660 Level 1, 2, 3, and Joliet
  • Linux: ISO 9660 Level 1, 2 (I'm not sure about Lvl 3, someone update this please), Joliet and Rock Ridge
  • Mac OS 7 to 9: ISO Level 1, 2. Optional free software supports Rock Ridge and Joliet: Joke Ridge and Joliet Volume Access.
  • Mac OS X: same as Linux, I believe.

(article edited by tempel on June 7, 2002)

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