HRM
Zilog
133ues
the
FRD
(format
read)
packet
command.
HRM
This
reads
only
the
header
portions
of
sectors
begin-
ning
at:
cyl,head,sec.
Dsec
sector
headers
are
read.
Six
words
of
data
are
returned
for
each
sector
read,
and
that
data
begins
at
<rseg>roff.
The
six
words
returned
for
each
sector
15 14 13 o
+--+--+--+----------------------------+
o
lET:ECIEPl
:
+--+--+--+----------------------------+
2 :
CYLINDER
:
r-------------------------------------+
4 l
HEAD
:
+--+--+-------------------------------+
6
lFLlSPl
SECTOR
:
+--+--+-------------------------------+
8 :
ECC
M.S.H.
:
+-------------------------------------+
10 I
ECC
L.S.H.
:
+-------------------------------------+
where,
ET
flags
the
last
sector
on
a
track
EC
flags
the
last
sector
on a
cylinder
EP
flags
the
last
sector
on
a
pack
FL
flags
a
bad
sector
SP
flags
a
spare
sector
ECC
M.S.H.
and
ECC
L.S.H.
are
the
high
and
low
parts
of
the
ECC
(checksum)
for
the
header
portion
of
the
sector.
EXAMPLE:
FRD
1 0 33
400
3 0
The
headers
of
33
sectors
beginning
head#3,
sector#
0
are
read
into
<1>0.
word s
long.
wit
hey
1
iF
4Q0 ,
Each
header
is
6
COMMAND:
HELP
DESCRIPTION:
Displays
a
list
of
command
names
and
their
parameters.
A-68
2ilog
A-68
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