Digital Equipment RW504-ZA, Service Manual

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6.5.3 Optical Disk Layout—1.3-Gbyte Capacity
This section highlights some of the aspects of 1.3-Gbyte Capacity optical disks as
outlined by ECMA 184.
The disk is divided into various zones, similar to the 650-Mbyte capacity. See
Figure 6–4. In addition to the User Zone, where user data is stored, there are
other zones including the PEP and SFP zones. Both the PEP and SFP contain
information prerecorded by the media manufacturer and cannot be altered by
a drive. They contain information about media parameters that the drive uses
to read from and write to the optical disk. Consult the ISO standard for more
information.
6.5.4 User Zone Layout—1.3-Gbyte Capacity
The User Zone consists of Defect Management Area (DMAs), and User Area. The
DMAs contain information about the organization of the User Area into User
Groups and Spare Groups. The DMAs also contain a Primary Defect List (PDL)
and a Secondary Defect List (SDL) that provide information on the locations of
defects. The drive uses this information to perform defect management.
Although the User Zone consists of tracks and sectors, it is often easier to think
of it in terms of a large memory space of consecutive sectors. Figure 6–6 shows
the following parts of the User Zone for 1.3-Gbyte media.
1. Four Defect Management Areas (DMAs) each consisting of a
• Disk Definition Structure (DDS)
• Primary Defect List (PDL)
• Secondary Defect List (SDL)
2. Slipping Area
3. User Area consisting of
• g User Groups, of n sectors each
• g Spare Groups, of m sectors each
Note
g = 1 or 16
Figure 6–6 and Figure 6–7 show the User Zone Layout for 1.3-Gbyte, for both
g=1 and g=16, respectively. It is important to note one significant difference
between 650-Mbyte and 1.3-Gbyte media. Both types of media can contain
multiple groups, however the start of each group on 650-Mbyte media can ‘‘slip
out’’ with any slip spares found prior to that group. 1.3-Gbyte media establishes
6–14 Theory of Operation