IBM DTCA-24090 Hard Drive Specifications - Page 131

Read Sectors, 20h/21h

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12.16 Read Sectors (20h/21h) Command Block Output Registers Register 76543210 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 1L1DHHHH Command 0010000R Command Block Input Registers Register 76543210 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 HHHH Status ...See Below... Error Register 76543210 CRC UNC 0 IDN 0 ABT T0N AMN 0V0V0V0V Status Register 76543210 BSY RDY DF DSC DRQ COR IDX ERR 0V0V 0 V Figure 76. 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. Command Descriptions 123

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12.16
Read Sectors
(20h/21h)
Command Block Output Registers
Command Block Input Registers
Register
76543210
Register
76543210
Data
Data
Feature
Error
...See Below...
Sector Count
VVVVVVVV
Sector Count
VVVVVVVV
Sector Number
VVVVVVVV
Sector Number
VVVVVVVV
Cylinder Low
VVVVVVVV
Cylinder Low
VVVVVVVV
Cylinder High
VVVVVVVV
Cylinder High
VVVVVVVV
Device/Head
1L1DHHHH
Device/Head
HHHH
Command
0010000R
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
V
0
V
0
V
0
V
0
V
0
V
0
V
Figure 76. 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.
Command Descriptions
123