NOTE: This Technical Note has been
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What's Wrong with my High Sierra Disc?
Generally, if a Macintosh has problems with a High Sierra disc, it's because the disc in question doesn't really conform to the High Sierra specification. There are actually two specifications of the High Sierra format:
The Paper 28 May 1986 Working Paper for Information Processing -- Volume and File Structure of Compact Read Only Optical Discs for Information Interchange (known as the "High Sierra" specification.) We'll call discs conforming to this standard "High Sierra" discs.
The Paper ISO 9660 -- Volume and File Structure of CDROM for Information Interchange (known as the "ISO 9660" specification.) We'll call discs conforming to this standard "ISO" discs.
The two formats are identical in content; some fields have moved around enough to make the two formats require separate processing. Most discs pressed before 1988 are in the High Sierra format. This was the de facto standard while the international standard was being established. It appears that most discs pressed in the future will be in the ISO format.
Both standards require that you store information used to access files in two
formats; least significant byte first (lsb) order (i.e. the hex number
Some of the early systems which allowed you to create High Sierra or ISO discs contained errors in the build process such that the discs didn't fully conform to the standard. In most of the cases we've seen here at Apple, one of the fields in the Primary Volume Descriptor was incorrect.
Some typical bugs:
If you have a disc that you believe is in High Sierra or ISO format and the Macintosh rejects it, try the following.
AppleCD SC Developers Guide
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