Sharp MZ-3500 - Manual (Page 49)

MZ3500
o MFM method (double density)
The MFM method writes data on the basis of the condì
tion metntioned below, and it yields a data density two
times the data density of the MFM mode (The unneces
sary clock pulse is eliminated using this method )
(Condition) Clock IS written only when there is no data
Input data
0 ^ 0 ^ 0 1 Jl 0 1 1 1
0
JLJLJl 1 Jl
0 0
\ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ / \ /
Write data
n n nnn n nnn n
c c (C) I) (Ü 1
^ —
(C
1
'!)
(Cl
'!)
ICI DU
1 >
1 <
I 1 ------- ---------------------------------
(u ; d ( u
1
---- ►(
It)
I 3 m 2 m
Data that follows Data that precedes
2 m 4 M
The clock pulse (C) will be eliminated in above illustra
tion as there is no data preceding or following the clock
Because the data rate is 2ps for this method, it is
possible to obtain twice the density of the FM method
(4ps).
NOTE Three types of write data cycle* (2i* j ,<") i/is)
are used The read/write waveform is identical
to FM method
6) Media recording format
Media is formatted according to the IBM format
For Double side media, data is written on the front side
(head-1) and the reverse side (head-00)
Tracks, consists of 40 tracks, 00-39. (May also be called
cylinders)
Sector. 01-16
Recording density: 256 bytes/sector
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