2-4. POSITIONING MECHANISM
In
order
to
achieve high accuracy
in
track positioning,
the
head
is
positioned
by
a needle screw mechanism.
And a
'steppingmotor
(Head Position Actuator)
is
controlled through the posicast control method
to
do
the best performance.
The
stepping
motor
rotates
the
lead screw clockwise
or
counterclockwise
in
45°
increments. A
45°
rotation
of
the lead screw
moves
the
read/write head
one
track position. When
+5 V and +12 V Power
is
on,
the
Head Positioning
Actuator
positions
the
read/write head
at
TRACKOO.
And if the head
is
positioned
at
TRACK69, STEP
IN
command
is
rejected.
2-5.
DISK CHUCKING MECHANISM
A new medium utilizes a centering metal
hub
which
maintains excellent Track positioning accuracy
with-
out
causing eccentricity
or
chucking wear. (See
Figure 2-2.)
CONVENTIONAL
TYPE
NEW TYPE
Figure 2-2. DISK CHUCKING MECHANISM
2-6. READ/WRITE HEAD
The
OA-D30V head
is
a
!'lew
type
of
single element
ceramic read/write head with tunnel erase head
to
provide erased areas between
data
tracks.
The
head
core
is
Mn-Zn single crystal ferrite.
The
data
track
width
is
125
microns and guard band width
is
63
microns.
2-7.
RECORDING FORMAT
The
format
of
the data recorded on
the
disk
is
totally
a function
of
the
host system, and can be
designed around the users application
to
best take
advantage
of
the total available bits
that
can be
written
on
anyone
track. Figure
2-3
shows the
concept
of
the track format. And Figure 2-4 and
2-5 shows
the
typically recommended format.
2-8.
FLOPPY DISK CONTROLLER CHIPS
There are some
LSI
FLOPPY DISK CONTROLLER
(FDC) Chips. Particularly NEC
J,LPD765
(Intel 8272)
and NEC
J,LPD745
can format easily.
The
format
of
Figure 2-4 can be obtained by
J,LPD765
and
that
of
Figure 2-5 can be obtained by
J,LPD745.
SONY
recommends
J,LPD745
for more
data
capacity.
/
/
/
/
/
./
/
/'
./
/
SECTOR
CYLINDER
PHYSICAL:
INDEX~,
~
~W~®(@J
®.-m
~~f-t--L_--f~I.U.l.U.>.~~~-
-4-
L -J
:ECTOR
1=:J
LSECTOR
N
L-i
PREAMBLE
POSTAMBLE
CD
GAP
1
@ 10
FIELD
@GAP
2
@
DATA
FIELD
® GAP 3
®GAP
4
SECTOR
FORMAT
CD
SYNC
@ 10 ADDRESS
MARK
@
CYLINDER
NUMBER
@
HEAD
NUMBER
® RECORD
NUMBER
® RECORD
LENGTH
(j) CRC
® GAP 2
®
SYNC
@
DATA
ADDRESS
MARK
@
DATA
@ CRC
@ GAP 3
Figure 2-3. TRACK FORMAT
To Next Page
Loading...
