Introduction

Under DOS (and Windows, which uses the DOS file system) files are written to both hard and floppy disks with a so-called FAT (File Allocation Table) file system. Files on a CD-ROM are written to a different standard called ISO 9660. Before ISO 9660, all CD-ROM discs could be read by all CD-ROM drives; however, CD-ROM drives were not supported by and readily available computer operating system. Application developers were required to have software device drivers for each computer and CD-ROM drive combination that they wanted to support. In addition, most applications require a file structure and this had to provided by each developer as well. Thus, application developers usually employed a systems house to provide device drives and file system software as well as build and retrieval engines. Enhancements to retrieval engines and support for additional drive types are requested by application development as a result. Thus, the systems houses had to spend critical resources to develop these drivers. An industry standard to address the file system file is needed and a committee called High Sierra is therefore formed. The High Sierra proposal was designed to enable data interchange between computers using standardized software so that when a computer is equipped for either High Sierra or ISO 9660, data on any properly encoded CD-ROM may be read using standard operating system instructions such as list directory, open, read and close.

ISO 9660 is rather complex and poorly written, and obviously contains a number of diplomatic compromises among advocates of DOS, UNIX, MVS and perhaps other operating systems.The simplified version presented here includes only features that would normally be found on a CD-ROM to be used in a DOS system and which are supported by the Microsoft MS-DOS CD-ROM Extensions (MSCDEX). It is based on ISO 9660, on certain documents regarding MSCDEX (version 2.10), and on the contents of some actual CD-ROM's.

Author

ISO 9660 was written by Edmund Fung, a member of the Porta-Amp team.

Testing and suggestions were provided by the rest of the Porta-Amp team: Kevin Mlazgar, Dan Leder, Danny Islam, and John Koob. Please give them credits.

References

Philip J. Erdelsky San Diego, California USA "ISO 9660 Simplified for DOS/Windows" http://www.alumni.caltech.edu/~pje/