Read Full - HP C2488A Technical Reference Manual

Read Full
The READ FULL command allows the Initiator to request all available information fields for
the specified logical or physical block. This information includes the header, data, and ECC
field contents. The Target returns to the Initiator a complete image of one physical block.
Included with the contents of the physical 'block is a header that defines the amount and type
of data available.
Note For this command to succeed, the header of the sector prior to the requested
sector must be readable.
Read Full Command Descriptor Block (COB)
Bit
Byte
7
I
6
I
5
I
4
I
3
I
2
I
1
I
0
00
Opcode = FOH
01
Logical Unit Number
I
Reserved
I
PHYS
02-05
(MSB=02) Address (LSB=05)
06 Reserved
07-08 (MSB=07) Allocation Length
(LSB=08)
09
Control Byte
Address. This field specifies which block to return.
PHYS (Physical Address). The interpretation of the address is determined by the state of the
PHYS bit. If PHYS is set to zero (0), the Address field is treated as a logical block address
per normal conventions and all normal position verifications are performed. The first physical
block in the specified logical block is returned. To access all physical blocks, the Initiator must
use the MODE SELECT command to set the logical block size equal to the physical block
size (normally 512 bytes). Otherwise, only the first physical block in each logical block is
accessible. ..'
If PHYS is set to one (1), the Address field is treated as a physical block address with the
Address field defined as follows:
• Byte 2: Physical Cylinder Address (MSB)
• Byte 3: Physical Cylinder Address (LSB)
• Byte 4: Head Address
• Byte 5: Physical Sector Address
Allocation Length.
This field specifies the number of bytes the Initiator is prepared to accept. If the number of
bytes available from the Target is greater than that specified in the CDB, the data will be
truncated to the Allocation Length value. The typical allocation length for a device formatted
with a 512 byte data field is 548.
B·18 Vendor Unique Command Descriptions
DRAFT
1/18/93 09:58