Read Headers - HP C2488A Technical Reference Manual

Read Headers
The READ HEADERS command will read all the headers on the track specified by the
Address field and return the requested number of bytes. The header information will always
be returned starting from physical sector 0 of the addressed track regardless of the addressed
block or sector.
READ HEADERS Command Descriptor Block (CDB)
Bit
Byte
7
I
6
I
5
i
4
i
3
i
2
i
1
i
0
00 Opcode = EEH
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
PHYS (Physical Address). If the PHYS bit is set to one (1), the address field is interpreted as
a physical address in the following format:
• Byte 2: Cylinder Address (MSB)
• Byte 3: Cylinder Address (LSB)
• Byte 4: Head Address
• Byte 5: Sector Address (Ignored)
If PHYS is set to zero (0), the address is assumed to be a logical address.
Address. This field specifies which track to read.
Allocation Length. A value of zero (0) in this field will cause a seek to the addressed track
with the header information read from the disk but no data transfer to the Initia.tor.
B·20 Vendor Unique Command Descriptions DRAFT
1/i8/93 09:58