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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
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