The following applies to all higher end PSR models. This would include the PSR-1000/2000; 1100/2100; 1500/3000; and ALL PSR "S" Series Models (with exception of the PSR-S550/650, which in this respect, are more similar to the entry level models). It excludes entry level PSR Models and the top-of the-line Tyros models:
To answer Carlos' question up front, NO! The above listed models can only split the keyboard at one point (either the default point or a user definable point), with the following exception. The left tone split point and the accompaniment (Chord) control split point can be set separately. In that case, the Chord "zone" is lowest or left most, and the left tone "zone" is immediately above that. So, in that sense, the keyboard can be split three ways, but the left most "zone" is predefined as the Chord control "zone". Other than its split point, it is not user definable/assignable. To the right of the split point, two individually switched voices (tones) can be switched on, either singly or together (layered), but to the left of the split point, action is determined by the combined status of the left/lower tone ON/OFF switch AND the auto- accompaniment (rhythm/one-man-band) switch. When both left/lower tone switch and accompaniment switch are off, the active right tones are spread across the entire keyboard - ala standard piano. When the left tone switch is on and the accompaniment switch is off, the active right tones appear above the split point and the selected left tone is applied below the split point in standard split operation. When the left tone switch is off and the accompaniment switch is on, the keyboard acts as a standard one-man-band arranger. When both the left tone switch and accompaniment switch are on, both the left tone and the accompaniment are applied below the split point. In FULL KEYBOARD fingering mode, the active right tones are spread across the entire keyboard along with the auto accompaniment, but only notes below (left) of the split point are parsed for accompaniment control. AI FULL KEYBOARD fingering mode allows similar performance, except the entire keyboard is parsed for accompaniment control. When split mode is added to this, right and left tones are confined to their own zones, but the entire keyboard is still parsed for accompaniment control. The top-of-the-line Tyros models operate very similar to this, with the addition of a third right voice (tone), but there is still only one common split point for all three right tones. While the locations and relative positions vary from model to model, there are two sets of three buttons which control these tones. The PART SELECT buttons are for assigning a tone to each PART (RIGHT-1, RIGHT-2, LEFT) and the PART ON/OFF buttons are obviously for turning each of the PARTS on or off during a performance.
And . . . . So . . . . What are my credentials for all of this ? . . . . I have been a PSR-3000 owner/player for soon-to-be eleven years. Other than expandability added with the PSR-S950 and the real-time DJ features added with the S970, if you've played one, you've pretty much played them all. Aside from diskette vs Smart Media Card vs USB Flash Drive, the number of tone/rhythm presets, and sound quality the basic features/operations don't really change all that much from one model to the next.