Deskstar 7K250 Hard Disk Drive Specification
138
12.17 Read DMA Queued Ext (26h)
Table 77: Read DMA Ext Command (25h)
This command executes in a similar manner to a READ DMA command. The device may perform a bus release or
it may execute the data transfer without performing a bus release if the data is ready to transfer.
If the device performs a bus release, the host shall re-select the device using the SERVICE command.
When the data transfer is begun, the device does not perform a bus release until the entire data transfer has been
completed.
Output parameters to the device
Feature Current
The number of sectors to be transferred low order, bits (7:0).
Feature Previous
The number of sectors to be transferred high order, bits (15:8). If 0000h in the
Feature register is specified, then 65,536 sectors will be transferred.
Sector Count Current
Bits (7:3) (Tag) contain the Tag for the command being delivered.
Sector Number Current
LBA (7:0)
Sector Number Previous
LBA (31:24)
Cylinder Low Current
LBA (15:8)
Cylinder Low Previous
LBA (39:32)
Cylinder High Current
LBA (23:16)
Cylinder High Previous
LBA (47:40)
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 Low
- - - - - - - -
Data Low
- - - - - - - -
Data High
- - - - - - - -
Data High
- - - - - - - -
Feature
Current
V V V V V V V V
Error see
below
Previous
V V V V V V V V
Sector
Count
Current
V V V V - - - -
Sector
Count
HOB=0
V V V V V V V V
Previous
- - - - - - - -
HOB=1
- - - - - - - -
Sector
Number
Current
V V V V V V V V
Sector
Number
HOB=0
V V V V V V V V
Previous
V V V V V V V V
HOB=1
V V V V V V V V
Cylinder
Low
Current
V V V V V V V V
Cylinder
Low
HOB=0
V V V V V V V V
Previous
V V V V V V V V
HOB=1
V V V V V V V V
Cylinder
High
Current
V V V V V V V V
Cylinder
High
HOB=0
V V V V V V V V
Previous
V V V V V V V V
HOB=1
V V V V V V V V
Device/Head
1 1 1 0 - - - -
Device/Head
- - - - - - - -
Command
0 0 1 0 0 1 0 1
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
V
0
V
0
V
0
V
0
V
0
V
-
0
-
V
Summary of Contents for Deskstar 7K250
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