SanDisk CompactFlash Extreme III - Manual (Page 71)

SanDisk CompactFlash Card OEM Product Manual ATA Command Description
5.1.12 Read Long Sector–22H, 23H
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 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.
Table 5-19 Read Long Sector
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
5.1.13 Read Sector(s)–20H, 21H
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 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.
Table 5-20 Read Sector(s)
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
5.1.14 Read Verify Sector(s)–40H, 41H
This command is identical to the Read Sectors command, except that DRQ is never set and no
data is transferred to the host. When the command is accepted, the card sets BSY.
© 2007 SanDisk Corporation 5-17 Rev. 12.0, 02/07