HP C2246 Technical Reference Manual page 136

Media Test
The MEDIA TEST command instructs the Target to automatically perform testing over a
specified area of the media. ·
Media Test Command Descriptor Block (CDB)
Bit
Byte 1
I
6
I
5
I
4
I
3
I
2
I
1
I
0
00 Opcode=
FlH
01 Logical Unit Number
I
WRT
I
PHYS
I
INT
I
RND
I
RST
02-05
(MSB=02} Address (LSB=05)
06_..:.08 (MSB=06) Transfer Length (LSB=08}
09 Control Byte
WRT (Write). This bit defines the type of test to be performed on the specified media area.
If WRT is set to zero (0), the Target performs a read; if WRT is set to one (1), the Target
performs a write operation.
PHYS (Physical Address). If PHYS is set to zero (0), the address is assumed to be a logical
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: Physical Cylinder Address (MSB)
• Byte 3: Physical Cylinder Address (LSB)
• Byte 4: Head Address
• Byte 5: Physical Sector Address
The Initiator can specify the test area as follows:
If the values of the specified physical address (cylinder, head, sector) are within the
physical boundaries of the drive under test, it wiU seek to that location and begin the
test.
If any of the values of the specified physical address are greater than the drive
boundaries, it will perform the test on the following area:
Out-Of-Bound Value(s)
Cylinder Head Sector Test Area
Outside Inside Outside The entire
surface of
the addressed head
Inside Outside Outside The entire addressed cylinder
Inside Inside Outside The entire track relative to the addressed head and cylinder
Outside Outside Outside The entire volume
INT (Internal Pattern). This bit selects the source of the data pattern used when a write test
is selected. If INT is set to one (1), the Target uses an internally generated worst.:case data
pattern (6DBH). If INT is set to zero (0), the current contents of the first logical block of the
Target's data buffer is used for the write pattern. Therefore, immediately preceding a MEDIA
TEST command with INT set to zero (0), the Initiator should perform a WRITE BUFFER
command (of at least one block length) which loads the desired data pattern into the data
buffer. If WRT is set to zero (0), INT must also be set to zero (0).
B-16 Vendor Unique Command Descriptions