ISO 9660 - Compact Disk (CD) on different Operating System (OS)
When I was recovering some of my files from a crashed hard disk, I was wondering if a CD written in one OS could be read by another OS. I was recovering the files using Knoppix (a Linux distribution), and then writing it to a CD. If I were to use these files in a Windows XP system, I had to make sure that the CD could be read. I did some research around and found that the Data CD format is indeed compatible across multiple OS because a file system called ISO 9660 is used.
ISO 9660 is a international standard that defines a file system for writing on the CD media so that it can be read by computers powered by Microsoft Windows, Mac OS, Unix and Linux variants. ISO 9660 was based on the High Sierra file system format that arranged file information in a dense and sequential format. High Sierra format was then used and the standard ISO 9660 was formulated.
ISO 9660 has its initial set of bytes (starting from address zero), set aside for system usage. This allows one to create CDROM disks that can be used as a boot disk. Then after some more reserved space for future expansion, a series of volume descriptors are written. This, on the bare minimum, contains the Primary Volume Descriptor that is a standard for ISO, and a variable length Ending Volume Descriptor that allows for variations from the ISO. Directory, sub-directory and file entries are written following that. And after that, the actual data that is contained in a file is written.
Such a kind of setup also allows one to create a CDROM disk image. One can create a .ISO file that is the exact replica of how it has to be written onto a CDROM disk. This .ISO file can be shared across the network or the internet and the end-user can use this .ISO image file to write (burn) on to a CDROM disk to get a ISO 9660 complaint Data disk.
There is a lot of material on CDROM in the internet. Here are some of the links that you may find helpful for further study:
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