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11.16 Read Multiple (C4h)
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
Figure 114. Read Multiple Command (C4h)
The Read Multiple 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. Command execution is identical to
the Read Sectors command except that an interrupt is generated for each block (as defined by the Set
Multiple command) instead of for each sector.
Output parameters to the device
Sector Count
Sector Number
Cylinder High/Low
H
Input parameters from the device
Sector Count
7 6 5 4 3 2 1 0
- - - - - - - -
- - - - - - - -
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 V V V V
1 L 1 D H H H H
1 1 0 0 0 1 0 0
4
3
2
1
IDN
0
ABT
T0N
AMN
V
0
V
0
The number of continuous sectors to be transferred. If zero is specified, 256
sectors will be transferred.
The sector number of the first sector to be transferred. (L=0)
In LBA mode this register contains LBA bits 0 - 7. (L=1)
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)
The head number of the first sector to be transferred. (L=0)
In LBA mode this register contains LBA bits 24 - 27. (L=1)
The number of requested sectors not transferred. This will be zero unless an
unrecoverable error occurs.
Deskstar 120GXP hard disk drive specifications
Command Block Input
Register
Data
Error
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Status
Status Register
0
7
6
5
BSY
RDY
DF
V
0
V
0
134
Registers
7 6 5 4 3 2 1 0
- - - - - - - -
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
V V V V V V V V
- - - - H H H H
see below
4
3
2
1
DSC
DRQ
COR
IDX
ERR
V
–
0
–
0
V
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