Optical Disk Formats

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In addition to the magnetic disk formats, Windows 2000 also supports two different optical file formats: CDFS and UDF. The CD-ROM File System (CDFS) is based on ISO 9660, a read-only file system standard written by an industry group, High Sierra. The group got that name from its initial meeting in 1985 at Del Webb's High Sierra Hotel and Casino at Lake Tahoe, Nevada, where representatives of Apple, Microsoft, Sony, and others began cooperating on development of a non-proprietary file system format for CD-ROM. The initial standard was named after the group, but the International Organization for Standardization (ISO) requested that an international version of the standard be released. This version was formalized as ISO 9660 (Volume and File Structure of CD-ROM for Information Interchange). Macintosh, DOS, Windows, UNIX, and Linux all support the standard, which calls for 2048-byte physical sectors. Level 1 of CDFS, like MS-DOS, follows the 8.3 file name format. Directories are limited to 8-character names and 8 nested levels. Levels 2 and 3 permit longer file and directory names, up to 32 characters, and allow the use of lowercase letters. Microsoft developed an extension to ISO 9660, called Joliet, which is supported in Windows 95/98/2000/Me/NT4.0/.NET, as well as Macintosh and Linux. Joliet allows the use of Unicode characters in file names of up to 64 characters.

Universal Disk Format (UDF) is a later standard created in 1995 by the Optical Storage Technology Association and defined in ISO 13346. It permits 255-character names with a maximum path length of 1023 characters and can be used with CD-ROMs, CD-Rs, CD-RWs, and DVD-ROMs. While ISO 9660 calls for data to be written continuously to the disk, UDF utilizes packet writing. Windows 98 and later versions of Windows support the UDF format, although only for reading, not writing, files. To write to CDs or DVDs requires additional software.

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