286
Western Digital Hard Disk Drive OEM Specification
11.60
Write DMA (CAh/CBh)
Com m and Block Output Registers
Com m and Block Input Registers
Register
7
6
5
4
3
2
1
0
Register
7
6
5
4
3
2
1
0
Data
-
-
-
-
-
-
-
-
Data
-
-
-
-
-
-
-
-
Feature
-
-
-
-
-
-
-
-
Error
…See Below …
Sector Count
V
V
V
V
V
V
V
V
Sector Count
V
V
V
V
V
V
V
V
Sector Number
V
V
V
V
V
V
V
V
Sector Number
V
V
V
V
V
V
V
V
Cylinder Low
V
V
V
V
V
V
V
V
Cylinder Low
V
V
V
V
V
V
V
V
Cylinder High
V
V
V
V
V
V
V
V
Cylinder High
V
V
V
V
V
V
V
V
Device/Head
1
L
1
D
H
H
H
H
Device/Head
-
-
-
-
H
H
H
H
Command
1
1
0
0
1
0
1
R
Status
…See Below …
Error Register
Status Register
7
6
5
4
3
2
1
0
7
6
5
4
3
2
1
0
CRC
UNC
0
IDN
0
ABT
T0N
AMN
BSY
RDY
DF
DSC
DRQ
COR
IDX
ERR
V
0
0
V
0
V
0
0
0
V
0
V
-
0
-
V
Table 251 Write DMA Command (CAh/CBh)
The Write DMA command transfers one or more sectors of data from the host to the device, then the data is written
to the disk media.
The sectors of data are transferred through the Data Register 16 bits at a time.
The host initializes a slave-DMA channel prior to issuing the command. Data transfers are qualified by DMARQ and
are performed by the slave-DMA channel. The device issues only one interrupt per command to indicate that data
transfer has terminated and status is available.
If an uncorrectable error occurs, the write will be terminated at the failing sector.
Output Parameters To The Device
Sector Count
The number of continuous sectors to be transferred. If zero is specified, then 256
sectors will be transferred.
Sector Number
The sector number of the first sector to be transferred. (L=0)
In LBA mode, this register contains LBA bits 0
– 7. (L=1)
Cylinder High/Low
The cylinder number of the first sector to be transferred. (L=0)
In LBA mode, this register contains LBA bits 8
– 15 (Low), 16 – 23 (High). (L=1)
H
The head number of the first sector to be transferred. (L=0)
In LBA mode, this register contains LBA bits 24
– 27. (L=1)
R
The retry bit, but this bit is ignored.
Input Parameters From The Device
Sector Count
The number of requested sectors not transferred. This will be zero, unless an
unrecoverable error occurs.
Sector Number
The sector number of the last transferred sector. (L=0)
In LBA mode, this register contains current LBA bits 0
– 7. (L=1)
Cylinder High/Low
The cylinder number of the last transferred sector. (L=0)
In LBA mode, this register contains current LBA bits 8
– 15 (Low), 16 – 23 (High). (L=1)
H
The head number of the last transferred sector. (L=0) In LBA mode, this register
contains current LBA bits 24
– 27. (L=1)
