Filter
Top Products
ATA Bus Interface and ATA Commands
Maxtor D540X-4K 20.4/40.0/60.0/80.0 GB AT 6-9
READ DEFECT LIST LENGTH Command Bytes
Registers 1F2h through 1F5h must contain the exact values
shown. These values function as a key. The drive issues the
message ILLEGAL COMMAND if the bytes are not entered
correctly.
The READ DEFECT LIST command is an extended AT command that enables the
host to retrieve the drive’s defect list. The host begins by writing to address 1F6h to
select the drive. Then the host writes to addresses 1F2h – 1F5h using values indicated
in Table 6-4. When the host subsequently writes the extended command code F0h to
address 1F7h, the drive sets BSY, retrieves the defect list, sets DRQ, and resets BSY.
The host can now read the requested number of sectors (512 bytes) of data. An
INTRQ precedes each sector. Bytes 1F2h and 1F3h contain the 2-byte number of
sectors that the host expects to read, with address 1F2h containing the LSB (see Table
6-4). The sector count (1F2h – 1F3h) may vary from product to product and if the
wrong value is supplied for a specific product, the drive responds by setting the ABRT
bit in the Error register. If the host does not know the appropriate sector count for a
specific product, it can issue the Read Defect List Length command, described in the
previous section to set up the task file for the Read Defect List command.
Sector
Count
0 Defect List Subcode Length in Sectors
(LSB)
Sector
Number
FFh Password Length in Sectors
(MSB)
Cylinder
Low
FFh Password FFh
Cylinder
High
3Fh Password 3Fh
Device/
Head
AXh (Drive 0) Drive Select AXh = Drive 0
BXh (Drive 1) — BXh = Drive 1
Command F0h Extended Command
Code
Status Register