MPI 40 Series - FM Encoding; MFM Encoding

I NOTE
Timing diagrams, figures 3-14 and 3-15,
show data as "Low True".
3.7.1.1 FM Encoding
FM (frequency modulation) encoding has the following rules:
1
A. A data bit, if it is a "1", occurs at the center of the
bit cell.
B. A clock bit occurs at the start of the bit cell.
0 0 0
1
0
1
1
BIT CELL= Bµs
Figure 3-14: FM Encoding
3.7.1.2 MFM Encoding
MFM (modified FM) encoding has the following rules:
A. A data bit, if it is a "1", occurs at the center of the
bit cell.
B. A clock bit occurs at the start of the bit cell, but only
if no data bit occurred in the previous bit cell and no
data bit will occur in the current bit cell.
Li Li LI
Li LI Lr
1
0
I 0
I
0
1
0
1
1
I
BIT CELL= 4µs
Figure 3-15:
MFM Encoding
3-24