High Sierra Format

High Sierra Format (HSF) is the early logical file system used for CD-ROMs. The ISO 9660 standard is based on revised HSF.

Compact Discs were originally developed for recording music, but soon were used for recording data as they allowed recording of large amounts of information in a reliable, economic manner. At first every CD-ROM maker designed their own method of storing data, as there were no standards except at the very lowest level. There was a need for a stable standard for organizing data on compact disks into logical units such as files. In October 1985 several companies invited experts to participate in the development of a working paper for such a standard. In November 1985, representatives of 12 computer hardware manufacturers gathered at the High Sierra Hotel and Casino (currently called the Hard Rock Hotel and Casino) near Lake Tahoe, California. This group became known as the High Sierra Group.

Present at the meeting were representatives from the following companies:

• Apple Computer
• Digital Equipment Corporation (DEC)
• Hitachi
• LaserData
• Microsoft
• 3M
• Philips
• Reference Technology Inc.
• Sony Corporation
• TMS Inc.
• VideoTools
• XEBEC

The meeting report was released in May 1986 and the High Sierra Group proposal was submitted to ECMA. This led to the issue of the ECMA-119 standard in December 1986, later adopted as ISO 9660.

HSF was built upon the Yellow Book CD-ROM standard for data CDs, which itself was so open ended it would otherwise lead to diversification and creation of many incompatible data storage methods.

The creation of ISO 9660 was needed because the HSF was geared primarily towards the needs of the US market. The international extensions are the bulk of the differences between the formats.

The High Sierra Format was mainly used in the United States. The ISO 9660 format is used globally. Currently, High Sierra Format CD-ROMs are rarely encountered.