Deskstar T7K250 Hard Disk Drive Specification
155
12.19 Read Long (22h/23h)
Table 96: Read Long (22h/23h)
The Read Long command reads the designated one sector of data and the ECC bytes from the disk media. It then
transfers the data and ECC bytes from the device to the host.
After 512 bytes of data have been transferred, the device will keep setting DRQ = 1 to indicate that the device is
ready to transfer the ECC bytes to the host. The data is transferred 16 bits at a time and the ECC bytes are trans-
ferred 8 bits at a time. The number of ECC bytes are 4 or 40 according to the setting of Set Feature option. The
default setting is 4 bytes of ECC data.
The command makes a single attempt to read the data and does not check the data using ECC. Whatever is read is
returned to the host.
Output parameters to the device
Sector Count
This indicates the number of continuous sectors to be transferred. The Sector Count must
be set to one.
Sector Number
This indicates the sector number of the sector to be transferred. (L = 0)
In LBA mode, this register contains LBA bits 0–7. (L = 1)
Cylinder High/Low
This indicates the cylinder number of the sector to be transferred. (L = 0)
In LBA mode, this register contains LBA bits 8–15 (Low), 16–23 (High). (L = 1)
H
This indicates the head number of the sector to be transferred. (L = 0)
In LBA mode, this register contains 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
Sector Number
This indicates the sector number of the transferred sector. (L = 0)
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
0 0 0 0 0 0 0 1
Sector Count
- - - - - - - 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
0 0 1 0 0 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
0
0
0
V
0
V
0
V
0
V
0
V
-
0
-
V
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