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6.1.11
Read Long Sector - 22H, 23H
Bit ->
7
Command (7)
C/D/H (6)
1
Cyl High (5)
Cyl Low (4)
Sec Num (3)
Sec Cnt (2)
Feature (1)
The Read Long command performs similarly to the
Read Sector(s) command except that it returns 516
bytes of data instead of 512 bytes. During a Read
Long command, the CompactFlash Memory Card
does not check the ECC bytes to determine if there
has been a data error. Only single sector read long
operations are supported. The transfer consists of
6.1.12
Read Sector(s) - 20H, 21H
Bit ->
7
Command (7)
C/D/H (6)
1
Cyl High (5)
Cyl Low (4)
Sec Num (3)
Sec Cnt (2)
Feature (1)
This command reads from 1 to 256 sectors as
specified in the Sector Count register. A sector
count of 0 requests 256 sectors. The transfer begins
at the sector specified in the Sector Number
Register. When this command is issued and after
each sector of data (except the last one) has been
read by the host, the CompactFlash Memory Card
sets BSY, puts the sector of data in the buffer, sets
DRQ, clears BSY, and generates an interrupt. The
host then reads the 512 bytes of data from the
buffer.
SanDisk CompactFlash Memory Card Product Manual © 1998 SANDISK CORPORATION
CompactFlash Memory Card Product Manual
6
5
4
22H or 23H
LBA
1
Drive
Cylinder High (LBA 23-16)
Cylinder Low (LBA 15-8)
Sector Number (LBA 7-0)
6
5
4
20H or 21H
LBA
1
Drive
Cylinder High (LBA 23-16)
Cylinder Low (LBA 15-8)
Sector Number (LBA 7-0)
Sector Count
3
2
Head (LBA 27-24)
X
X
512 bytes of data transferred in word mode
followed by 4 bytes of random data transferred in
byte mode. Random data is returned instead of
ECC bytes because of the nature of the ECC system
used. This command has the same protocol as the
Read Sector(s) command.
3
2
Head (LBA 27-24)
X
At command completion, the Command Block
Registers contain the cylinder, head and sector
number of the last sector read. If an error occurs,
the read terminates at the sector where the error
occurred. The Command Block Registers contain
the cylinder, head, and sector number of the sector
where the error occurred. The flawed data is
pending in the sector buffer.
1
0
1
0
67
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