11.23 Read Sector(s) (20h/21h)
Command Block Output Registers
Register
Data
Feature
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Command
Error Register
7
6
5
CRC UNC
0
0
V
0
Table 117 Read Sector(s) Command (20h/21h)
The Read Sector(s) command reads one or more sectors of data from disk media, and then transfers the data
from the device to the host.
The sectors are transferred through the Data Register 16 bits at a time.
If an uncorrectable error occurs, the read will be terminated at the failing sector.
7
6
5
4
3
2
1
-
-
-
-
-
-
-
-
-
-
-
-
-
-
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
1
L
1
D
H
H
H
0
0
1
0
0
0
0
4
3
2
1
IDN
0
ABT T0N AMN
V
0
V
0
Hitachi hard disk drive specifications
Command Block Input Registers
0
Register
7
-
Data
-
-
Error
V
Sector Count
V
V
Sector Number
V
V
Cylinder Low
V
V
Cylinder High
V
H
Device/Head
-
R
Status
Status Register
0
7
6
5
BSY RDY
DF
0
0
V
0
167
6
5
4
3
2
1
-
-
-
-
-
-
...See Below...
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
V
-
-
-
H
H
H
...See Below...
4
3
2
1
DSC DRQ COR IDX ERR
V
-
0
-
0
-
V
V
V
V
H
0
V