85
Western Digital Hard Disk Drive OEM Specification
9.18.3
SCT Command Set
9.18.3.1
SCT Write Same (action code : 0002h)
Inputs: (Key Sector)
Word
Name
Value
Description
0
Action Code
0002h
This action writes a pattern or sector of data repeatedly to
the media. This capability could also be referred to as “Write
All” or “Write Same”.
1
Function Code
0001h
Repeat Write Pattern (Background Operation)
0002h
Repeat Write Sector (Background Operation)
0101h
Repeat Write Pattern (Blocking Operation)
0102h
Repeat Write Sector (Blocking Operation)
5:2
Start LBA
Qword
First LBA
9:6
Count
Qword
Number of sectors to fill
11:10
Pattern
Dword
If the Function Code is 0001h, this field contains a 32-bit
pattern that is written on the media starting at the location
specified in words two through five
255:12
reserved
0000h
Table 60 SCT Write Same (Inputs)
Outputs: (TF Data)
Command Block Input Registers (Success)
Error
00h
Sector Count
Reserved
Sector Number
Reserved
Cylinder Low
Number of sectors to transfer (LSB) = 01h
Cylinder High
Number of sectors to transfer (MSB) = 00h
Device/Head
Reserved
Status
50h
Table 61 Output Registers of SCT Write Same (Success)
The SCT Write Same command will begin writing sectors from Start LBA in incrementing order until Count sectors
have been written. A Count of zero means apply operation from Start LBA until the last user LBA on the drive is
reached. The HPA feature determines the last user LBA. This command will not write over a hidden partition when
hidden partitions are enabled using the Host Protected Area drive capabilities. Automatic sector reassignment is
permitted during the operation of this function.
If Start LBA or Start LBA + Count go beyond the last user LBA then an error is reported and the SCT command is not
executed. Issuing this command with a value of zero for Start LBA and Count will cause all LBAs of the drive to be
written the specified pattern.
Once the key sector has been issued, if the Function Code was 0002h or 0102h and the TF Data indicates that the
drive is ready to receive data, log page E1h should be written to transfer the data.
This command can change the Segment Initialized Flag. If the command writes all the user addressable sectors and
completes without encountering an error or being aborted, then the “Segment Initialized Flag” (bit 0 of the Status
Flags in the SCT Status. See
) shall be set to 1. A write to any user addressable sector on the drive (except
