ISO 9660: Difference between revisions

 

== Volume Descriptors ==

When preparing to mount a CD, your first action will be reading the volume descriptors (specifically, you will be looking for the Primary Volume Descriptor).

 

 

=== Volume Descriptor Type Codes ===

{| {{wikitable}}

! Value

When starting out with a basic CD, we are going to be interested in the Primary Volume Descriptor, which points us to the root directory and path tables, which both allow us to find any file on the CD. Using the path table is ideal for minimal implementations which do not wish to search the directory hierarchy node by node. This is slower (string comparisons across the entire filesystem) but easier to implement.

 

 

The first type of Volume Descriptor is the "Boot Record". The descriptor format is as follows:

 

 

=== The Primary Volume Descriptor ===

This is a lengthy descriptor, but it contains some very useful information for reading the rest of the file system.

{| {{wikitable}}

! Offset

 

==== Date and Time Format ====

The date / time format used in the Primary Volume Descriptor is:

 

 

All fields except for the offset from GMT are in ASCII digits. An unspecified date and time is represented by 16 '0' digits, followed by a zero in the last field.

 

== The Path Table ==