Fujitsu MAP3147FC, MAP3735FC Data Format, 7 Alternate block allocation by FORMAT UNIT command

Data Format

(1)Alternate block allocation during FORMAT UNIT command execution

When the FORMAT UNIT command is specified, the allocation of the alternate block to those defective sectors included in the specified lists (P, G, or D) is continued until all spare sectors in the same cell are used up. When they are used up, unused spare sectors in the alternate cylinder are allocated to the subsequent sectors in the cylinder by means of alternate sector treatment. Figure 3.7 is examples of the alternate block allocation during the FORMAT UNIT command execution.

: n represents a logical data block number

: Defective sector

: Unused spare sector

Figure 3.7 Alternate block allocation by FORMAT UNIT command

If the data block verifying operation (certification) is not permitted (DCRT flag = 0) in the FORMAT UNIT command, the IDD checks all initialized logical data blocks by reading them out after the above alternate block allocation is made to initialize (format) the disk. If a defective data block is detected during the check, the IDD allocates the alternate block to the defective data block. This alternate block allocation is made by means of alternate sector treatment only like processing by the REASSIGN BLOCKS command even if unused spare sectors exists in the same cell.

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