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MZJWt,
I
Pin No
SIgnal name
1/0
FunctIon
32,31
PSO, 1
0
Signal used to either advance or delay the wrtte data In wrttlng under the MFM mode,
to obtain timing adjustment for reading. The WDATA Signal
IS
controlled as shown
In
the table below
PSO
PS,
FM
MFM
0
0
Not changed Not changed
0
,
LATE
-
225-250ns
,
0
-
EARLY
225-250ns
,
,
-
-
23
RDATA
I
Read data from the drive unit consists of clock bits and data bits.
--------- --
22
WINDOW
I
Signal created In the VFO circuit which is used to sample RDATA. Phase syncroni2'
I
carried out In the FOC for RDATA data bits and WINDOW.
I
5-5. Data recording method
There are two ways of recording data; FM recording
method and MFM recording method.
2) MFM recording method
(1) Data bit
IS
placed in a middle of a bit cell.
(2) When the data bit
IS
"0", a clock bit is placed before
the current bit cell. (See Fig. 1)
o
o
o
As seen from the above illustration, bit density of the MFM
recording method is twice the FM recording method. In
other words, data density of the MFM recording method
doubles that of the FM recording method. For the
5-6. 1/0 port in the MFD interface
I/O port used in the MF D interface is as follows.
Lr-BUS
I/O
IOMF#F9·AO
OUT
DACK
D7
ME
D6
SCTRL
D5
TC
D4
OUT
TRIG
D3
SEL3
rmIF#F8·AO'
D2
~
EL2
Dl
SELl
])0
SELO
])2
M.ON
])1
IN
I~DEX
])0
PRQ
o
1) MF recording method
(1) Clock bit indicates a bit cell.
(2) Data bit is placed in a middle of a bit cell. (See Fig. 1.)
(FM recording method)
,L-_-t-
J
........ _ - -
(MFM recording method)
o
Model 3500, only side 0 of track 0 (128 bytes/sector! is
written in the FM mode and rest of other tracks are
recorded in the MFM mode.
Used for data transfer between the CPU and the FOC.
INT from the FOC is output enabled on INTFD.
FDO select signal output is enabled.
TC to FOC.
Trigger (motor on) of the timer (555)
Selects FDD 3
Selects F DO 2
Selects FDO 1
Selects FOD 0
ON/OFF state of the motor
INDEX signal from the motor
DRO from the FOC.
- 59-
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