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M 7 3500
Shown below is an enlarged view of data format
sequence Writing 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
ID section CRC check code
Size of data section
(00) H — 128 bytes
(01) H — 256 bytes
Sector number
Head number
(00) H
(01) H -* Head 1 (side 1)
• Track number
• ID address mark which begins the ID section
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)The head is loaded
(3)ID section is read and repeated until the desired section is reached
(4)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
51
DATA
AM DATA CRC CRC
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
(6)The sector of the identical ID is read and verified with the write data Because of thr pad dftei Ar.'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
(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