Product manual

CompactFlash Memory Card Product Manual Preliminary
SanDisk CompactFlash Memory Card Product Manual Rev. 8 © 2001 SANDISK CORPORATION
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6.1.11 Read Long Sector - 22H, 23H
Bit -> 7 6 5 4 3 2 1 0
Command (7)
22H or 23H
C/D/H (6)
1 LBA 1 Drive Head (LBA 27-24)
Cyl High (5)
Cylinder High (LBA 23-16)
Cyl Low (4)
Cylinder Low (LBA 15-8)
Sec Num (3)
Sector Number (LBA 7-0)
Sec Cnt (2)
X
Feature (1)
X
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 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.
6.1.12 Read Sector(s) - 20H, 21H
Bit -> 7 6 5 4 3 2 1 0
Command (7)
20H or 21H
C/D/H (6)
1 LBA 1 Drive Head (LBA 27-24)
Cyl High (5)
Cylinder High (LBA 23-16)
Cyl Low (4)
Cylinder Low (LBA 15-8)
Sec Num (3)
Sector Number (LBA 7-0)
Sec Cnt (2)
Sector Count
Feature (1)
X
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.
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.