Yamaha SY77 Operating Manual page 41

Data entry wheel
Data entry slider
If you want to decrease or increase the existing data value by a significant
amount, use the data entry wheel. As you rotate the wheel to the right
(clockwise) the data will increase, and as you rotate the wheel to the left
(counter-clockwise) the data will decrease. The wheel rotates freely; it modifies
the data by its movement, not by its position. Like the -1/+1 keys, the data
entry wheel modifies the existing value, but is more suitable for making larger
continuous changes. In job or voice directories, the wheel can be used to select
jobs and voices.
If you want to set a data value to some setting relative to the entire range of
that value (for example "maximum", "minimum", or "about 90% of maximum"),
use the data entry slider. When you move the slider, the data value is imme-
diately changed to correspond to the position of the slider. The range of the
slider will match the range of the parameter value. For example if the parameter
being modified has a value range of 0-127, pulling the slider fully towards you
will set a value of 0, and pushing the slider fully away from you will set a value
of 127. Setting the slider exactly in the middle of its range would set a value of
64.
Since the range of the slider always matches the range of the parameter you
are adjusting, there is no need to remember the range of the parameter; just
move the slider to the position that corresponds to the relative setting you want.
DATA ENTRY
(range of each parameter)
0-99 0-7 -50 – +50
99 7 +50
50 3 +0
0 0 –50
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