Table of Contents
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M 7 3500
Shown
below
is an enlarged view of
data format
sequence W r i t i n g starts as soon as the index hole comes
through the index detect hole
1 Track
Sector 01
Sector 02
Firnl ^p
DATA
DATA
I U
I I )
DA I A
<
[
t
I N D E X
\M
Start point
Hatched portion is
a recording gap
I D
AM
TT HH SS DL CRC CRC
DATA
AM
51
DATA
CRC CRC
ID section CRC check code
Size of data section
(00) H — 128 bytes
(01) H — 256 bytes
Sector number
Head number
(00) H -» Head 0 (side 0)
(01) H -* Head 1 (side 1)
• Track number
• ID address mark which
begins the ID section
Data
Data section
CRC check code
' Data address mark
(or delete address mark)
NOTE The delete address mark
is written to indicate invalid
data It is often written on
a new floppy disk as there are
no valid data on it
7) Formatting
To write the above format (ID section, data section, gap)
on an entire surface of a new floppy disk is called
formatting
Note 1 Formatting may also be called initialization. The
word "initialize" is also used as a software term to clear
the data section or to partition data area. Keep the
difference between formatting and initializing in mind.
Note 2
Unless formatting has been done on a properly
adjusted floppy disk drive unit, an erroe may occur on
another floppy disk drive unit
8) Data write procedure
Described next is the procedure to write data on the FD.
(1) The head is moved over the track to be written.
(2)
(3)
(4)
The head is loaded
ID section is read and repeated until the desired
section is reached
When the desired ID section is found, data is written
on that area (DATA AM is also written )
(5) The data thus written is now checked if it was
written correctly (read after write) The respective
ID section is read while the media makes a full turn
(6) The sector of the identical ID is read and verified
with the write data Because of thr
pad dftei A r . ' e
capability the possibility of an error in the written
data is quite low
9) Data read procedure
Described next is the procedure to read data from the
FD.
(1) The head is moved over the track tu -^ i ead
(2) The head is loaded
(3) The ID section is read and repeated until the desired
sector is reached
(4) When the identical IDsection is found, the <~i-m IP
that data section is then read
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