Sharp FDD-412A - Page 20

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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-—