Deskstar 7K250 Hard Disk Drive Specification
148
12.20 Read Multiple (C4h)
Table 86: Read Multiple (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. The command execution is identical to the
Read Sectors command with one exception: an interrupt is generated for each block—as defined by the Set Multi-
ple command—instead of for each sector.
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)
Input parameters from the device
Sector Count
This indicates the number of requested sectors not transferred. This number is zero unless
an unrecoverable error occurs.
Sector Number
This indicates the sector number of the transferred sector. (L = 0)
In LBA mode, this register contains current LBA bits 0–7. (L = 1)
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
V V V V V V V V
Sector Count
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
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
1 1 0 0 0 1 0 0
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
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