8.1.2
MFM Encoding
MFM (Modified Frequency Modulation) encoding records
twice the number of bits per inch (linear recording
density)
as FM encoding,
but has the same number of
flux changes per inch.
It does this by removing the
clock pulses, and shrinking the bit cell space by 50%.
See Figure 8-2 for specific details. Clock bits are
always written at the leading edge of the cell only if
no data bits are written
in either
the present
or
preceeding bit cells.