FlashDrive Product Manual
FlashDrive Product Manual © 1999 SANDISK CORPORATION
47
6.1.11
Read Long Sector - 22H or 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 FlashDrive 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 or 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 FlashDrive 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.
Summary of Contents for SD25B-100
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