ISO9660 format

Introduction:

   An ISO image is an archive file (also known as a disk image) of an optical disc in a format defined by the International Organization for Standardization (ISO). This format is supported by many software vendors, including WinTar. ISO image files typically have a file extension of .ISO but Mac OS X ISO images often have the extension .CDR. The name ISO is taken from the ISO 9660 file system used with CD-ROM media, but an ISO image can also contain UDF file system because UDF is backward-compatible with ISO 9660.

   The file format specified in the ISO 9660 standard is clearly a nearly universal file format, and standard disks can be read on a broad range of operating systems: MS-DOS, Windows, Unix, Linux and even Macintosh.

Format:

   As with any other archive, an ISO image includes all the data of files contained on the archived CD/DVD. They are stored in an uncompressed format. In addition to data of the files it also contains all the file system metadata, including boot code, structures, and attributes. ISO images do not support multi-track, thus they cannot be used for audio CDs, VCD, and hybrid audio CDs.

   These properties make it an attractive alternative to physical media for the distribution of software as it is simple to transfer over the Internet or via a LAN connection.

   ISO image is an unattached file format (like CAB and Zip): it merges a series of files into one single file according to a definite format. The most important feature of an ISO image is that it can be burned to a DVD, VCD, or CD by using an ISO image burner, like ISO Maker. ISO images are not meant to be burned to DVD-RW, and they should be burned to DVD-R, because DVD-R is more widely supported.

Typically Uses:

Some of the common uses include:

•   »   Distribution of software
•   »   Mount "virtual drives" which emulate physical CDs or DVDs, such as virtual computers. Better performance is achieved by running an ISO image, since I/O is many times faster with a hard drive than a CD/DVD drive.
•   »   To use software titles that are written in such a way that they require a physical disk to be present in order to run. Games are commonly in this category.
• For backup, such as PSP backups.

   WinTar can read and extract files from containing ISO9660-compliant CDROM images. It also has partial support for Rockridge extensions. In many cases, this can remove the need to burn a physical CDROM. It also avoids security and complexity issues that come with virtual mounts and loopback devices.

Related file formats

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•  archive file formats

•  CAB archive format

•  Zip archive format

•  Tar archive format

•  Pax archive format