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
(COB)
--
Bit
Byte
7
I
6
I
5
I
4
I
3
I
2
I
1
I
0
00
Opcode
=
FIH
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
will 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
Outside
Inside
Outside
Inside
Outside
Outside
Inside
Inside
Outside
Outside
Outside
Outside
Test
Area
The
entire surface of
the
addressed
head
The
entire
addressed
cylinder
The
entire
track
relative
to
the
addressed
head
and
cylinder
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
DRAFT
1/18/93 09:58
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