The original PS-3300 keyboard plays fully polyphonically at all times. Cherry PS-3300 lets you choose from a couple of mono or poly modes. Remember that these are set independently for each voice panel.
Keyboard Assign-
Last- One note sounds at a time with the most recently played note taking priority.
Lo- One note sounds at a time with the lowest note taking priority.
High- One note sounds at a time with the highest note taking priority.
Poly- Up to 24 notes sound at a time with most recently played notes taking priority.