Deskstar 7K250 Hard Disk Drive Specification
202
12.46 Write DMA (CAh/CBh)
Table 131: Write DMA (CAh/CBh)
The Write DMA command transfers one or more sectors of data from the host to the device and then the data is
written to the disk media.
The sectors of data are transferred through the Data Register16 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
This indicates the number of continuous sectors to be transferred. If zero is specified, then
256 sectors will be transferred.
Sector Number
This indicates the sector number of the first sector to be transferred. (L = 0)In LBA mode
this register contains the LBA bits 0–7. (L = 1)
Cylinder High/Low
This indicates number of the first sector to be transferred. (L = 0) In LBA mode this reg-
ister contains the LBA bits 8–15 (Low) and bits 16–23 (High). (L= 1)
H
This indicates the head number of the first sector to be transferred. (L = 0) In LBA mode
this register contains the LBA bits 24–27. (L = 1)
R
This indicates the retry bit. This bit is ignored.
Input parameters from the device
Sector Count
This indicates the number of requested sectors not transferred. The Sector Count will be
zero unless an unrecoverable error occurs.
Sector Number
This indicates the sector number of the last transferred sector. (L = 0) In LBA mode this
register contains the current LBA bits 0–7. (L = 1)
Command Block Output Registers
Command 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
V
V
-
0
-
V
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