Sharp MZ-3500 service manual Data

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 -» Head 0 (side 0)

(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 -^ 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