Table of Contents
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FDD412A/B
Recording
:
Data
Transfer
Pulse
Frequency
Method
Bee
Rate
Interval
(KB/s)
(us)
(kHz)
Frequency
Ratio
2.4.4
Data
Format
While
the
floppy
disk
needs
to be
initialized
in advance
to
the
pre-
determined
format,
the
data
format
must
meet
the
following
requirements.
IBM—based
data
formats
will
meet
all
of them.
(1)
Length
of
ID part
§ 224
us
(2)
Length
of gap
across
ID part
to data
part
(exclusive
of VFO
area)
2 512
us.
(3)
Length
of
gap
across
data
part
to
ID
part
(exclusive
of VFO
area)
2 544
us.
(4)
The VFO
area
should
be of 6 bytes
or more
for the FM method
and
12 bytes
or more
for
the MFM method,
with
the
(00)ig
pattern.
(5)
The
gap
pattern
should
be
(FF),g
for the FM method
and
(4E)j,
for
the
MFM
method.
(6)
The
gap
following
the
CRC
to be
updated
upon
writing
to
the
data
part
should
be of 1 byte
or
less.
(7)
Writing
solely
onto
the
ID part
(partial
write)
should
not
be
-
done.
As
an
example
of double
density
recording
onto
the
floppy
disk,
Fig.
2.7
shows
an IBM
format
and Table
2.7
fives
the
contents
of the
format.
INDEX
INDEX
1
!
~
1 track
_
Special
|
i
ID
eee
| record—_——+]
vy
|
|
I
:
c5[cifAle2[
1
|o3f
vata
|csf mw
|e3f
vata
|esjcr
~
!
Fig.
2.7
IBM Data Format
~14-—
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