Yamaha DX7 II FD Reference Manual page 27

Step In most musical circumstances, you will use the pitch wheel to create a smooth bending or
"sliding" of the pitch. However, sometimes you may wish to hear a "stepped" pitch bend,
during which the pitch is shifted by discrete steps as the pitch wheel is moved. The step
parameter provides this capability.
0 The pitch wheel bends the pitch smoothly with no steps.
1 The pitch is bent in steps of 1 semitone.
12 The pitch is bent in steps of 12 semitones (steps of 1 octave).
The step parameter has priority over the range parameter. If the step parameter is set to
anything other than 0, the range is automatically set to its maximum value of 12 and
cannot be adjusted.
Mode The pitch bend mode parameter allows you to specify which notes of a chord will be
affected by the pitch wheel. In addition, it determines whether or not pitch bend is applied
to notes sustained by the sustain pedal. The four available mode values have the following
effect on the pitch bend effect.
Pitch Bend Chord notes Applied to sound
Mode affected sustained by sustain pedal?
Normal all notes
_yes
Low lowest note only
_yes
High
hiahest note only _yes
Key on all notes no
There are many applications for this parameter.
Try
the high mode setting with normal (or
1 semitone stepped) full range pitch bend combined with the LFO multi mode vibrato on
a string ensemble voice. You can use the pitch wheel to play a high melody while the rest
of the notes are being sustained with the right hand.
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