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C141-E163 3-1
CHAPTER 3 Data Format
3.1 Data Space
3.2 Logical Data Block Addressing
3.3 Defect Management
This chapter explains data space definition, logical data block addressing, and defect management on the IDD.
3.1 Data Space
The IDD manages the entire data storage area divided into the following three data spaces.
• User space: Storage area for user data
• Internal test space: Reserved area for diagnostic purposes
• System space: Area for exclusive use of IDD itself
The user space allows a user access by specifying data. These space can be accessed with the logical
data block addressing method described in Section 3.2. The internal test space is used by Read/write
test of self-diagnostics test, but user can’t use direct access. The system space is accessed inside the
IDD at power-on or during the execution of a specific command, but the user cannot directly access
the system space.
3.1.1 Cylinder configuration
The IDD allocates cylinders to the user space, Internal test space, and system space. Figure 3.1 is the
cylinder configuration.
Spare areas (alternate areas) for defective sectors are provided in the user space. Several sectors in
the last track of one cylinder and several cylinders (alternate cylinders) in the user space are allocated
as alternate areas according to the user's assignment (MODE SELECT command). See Subsection
3.1.2 for details.