IBM DTLA-307075 Hard Drive Specifications - Page 149

Read Sectors 20h/21h

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12.17 Read Sectors (20h/21h) Command Block Output Registers Register 7 6 5 4 3 2 1 0 Data Feature Sector Count 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 High V V V V V V V V Device/Head 1 L 1 D H H H H Command 0 0 1 0 0 0 0 R Error Register 76543210 CRC UNC 0 IDN 0 ABT T0N AMN 0V0V0V0V Command Block Input Registers Register 7 6 5 4 3 2 1 0 Data Error see below Sector Count 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 High V V V V V V V V Device/Head - - - - H H H H Status see below Status Register 7 6 5 4 3 2 10 BSY RDY DF DSC DRQ COR IDX ERR 0 V 0 V - 0 -V Figure 103. Read Sectors Command (20h/21h) The Read Sectors command reads one or more sectors of data from disk media, 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. 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. If set to one, then retries are disabled. Deskstar 40GV & 75GXP hard disk drive specifications 137

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12.17 Read Sectors (20h/21h)
see below
Status
0 0 1 0 0 0 0 R
Command
- - - - H H H H
Device/Head
1 L 1 D H H H H
Device/Head
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
Cylinder Low
V V V V V V V V
Cylinder Low
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
Sector Count
V V V V V V V V
Sector Count
see below
Error
- - - - - - - -
Feature
- - - - - - - -
Data
- - - - - - - -
Data
7 6 5 4 3 2 1 0
Register
7 6 5 4 3 2 1 0
Register
Command Block Input
Registers
Command Block Output
Registers
V
–
0
–
V
0
V
0
V
0
V
0
V
0
V
0
ERR
IDX
COR
DRQ
DSC
DF
RDY
BSY
AMN
T0N
ABT
0
IDN
0
UNC
CRC
0
1
2
3
4
5
6
7
0
1
2
3
4
5
6
7
Status Register
Error Register
Figure 103. Read Sectors Command (20h/21h)
The Read Sectors command reads one or more sectors of data from disk media, 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.
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. If set to one, then retries are disabled.
Deskstar 40GV & 75GXP hard disk drive specifications
137