Fujitsu MHM2150AT Manual/User Guide - Page 94

READ SECTORS X'20' or X'21, Sector Number registers.

Page 94 highlights

5.3 Host Commands CM: Command register FR: Features register DH: Device/Head register ST: Status register CH: Cylinder High register ER: Error register CL: Cylinder Low register L: LBA (logical block address) setting bit SN: Sector Number register DV: Device address. bit SC: Sector Count register x, xx: Do not care (no necessary to set) Note: 1. When the L bit is specified to 1, the lower 4 bits of the DH register and all bits of the CH, CL and SN registers indicate the LBA bits (bits of the DH register are the MSB (most significant bit) and bits of the SN register are the LSB (least significant bit). 2. At error occurrence, the SC register indicates the remaining sector count of data transfer. 3. In the table indicating I/O registers contents in this subsection, bit indication is omitted. (1) READ SECTOR(S) (X'20' or X'21') This command reads data of sectors specified in the Sector Count register from the address specified in the Device/Head, Cylinder High, Cylinder Low and Sector Number registers. Number of sectors can be specified to 256 sectors in maximum. To specify 256 sectors reading, '00' is specified. For the DRQ, INTRQ, and BSY protocols related to data transfer, see Subsection 5.4.1. If the head is not on the track specified by the host, the device performs an implied seek. After the head reaches to the specified track, the device reads the target sector. If an error occurs, retry reads are attempted to read the target sector before reporting an error, irrespective of the R bit setting. The DRQ bit of the Status register is always set prior to the data transfer regardless of an error condition. Upon the completion of the command execution, command block registers contain the cylinder, head, and sector addresses (in the CHS mode) or logical block address (in the LBA mode) of the last sector read. If an unrecoverable error occurs in a sector, the read operation is terminated at the sector where the error occurred. C141-E104-03EN 5-17

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5.3
Host Commands
C141-E104-03EN
5-17
CM:
Command register
FR:
Features register
DH:
Device/Head register
ST:
Status register
CH:
Cylinder High register
ER:
Error register
CL:
Cylinder Low register
L:
LBA (logical block address) setting bit
SN:
Sector Number register
DV:
Device address. bit
SC:
Sector Count register
x, xx:
Do not care (no necessary to set)
Note:
1.
When the L bit is specified to 1, the lower 4 bits of the DH register and all
bits of the CH, CL and SN registers indicate the LBA bits (bits of the DH
register are the MSB (most significant bit) and bits of the SN register are
the LSB (least significant bit).
2.
At error occurrence, the SC register indicates the remaining sector count of data
transfer.
3.
In the table indicating I/O registers contents in this subsection, bit indication is
omitted.
(1)
READ SECTOR(S) (X’20’ or X’21’)
This command reads data of sectors specified in the Sector Count register from
the address specified in the Device/Head, Cylinder High, Cylinder Low and
Sector Number registers.
Number of sectors can be specified to 256 sectors in
maximum.
To specify 256 sectors reading, ‘00’ is specified.
For the DRQ,
INTRQ, and BSY protocols related to data transfer, see Subsection 5.4.1.
If the head is not on the track specified by the host, the device performs an
implied seek. After the head reaches to the specified track, the device reads the
target sector.
If an error occurs, retry reads are attempted to read the target sector before
reporting an error, irrespective of the R bit setting.
The DRQ bit of the Status register is always set prior to the data transfer
regardless of an error condition.
Upon the completion of the command execution, command block registers contain
the cylinder, head, and sector addresses (in the CHS mode) or logical block
address (in the LBA mode) of the last sector read.
If an unrecoverable error occurs in a sector, the read operation is terminated at the
sector where the error occurred.