These are the controls to the left of the virtual keyboard. They affect how Mercury-4 responds to incoming pitch bender control messages (the Jupiter-4's pitch bend joystick could affect much more than just pitch), portamento, and master transposition.
Bender Section
The original Jupiter-4 had a joystick bender control that moved on a horizontal axis; it had no performance control for initiating modulation. Roland made up for the lack of mod control with a clever joystick implementation that allowed the joystick to control VCO pitch, VCF cutoff, VCA volume, or LFO mod to VCO, VCF, or VCA. The joystick mod can be combined dependent on the switch positions, and can be a very a musical and creative approach
Bender Sensitivity- Globally sets maximum bend depth for VCO, VCF, and VCA switches set to the Bend position.
Bender LFO Amount- Globally sets maximum LFO modulation amount for VCO, VCF, and VCA switches set to the LFO position.
VCO switch- Determines how incoming pitch bender messages affect oscillator pitch.
LFO- Pitch bender applies LFO modulation to oscillator pitch. Upward bends adds positive modulation; downward bends add negative modulation.
Off- VCO mod disabled.
Bend- Behaves like a standard pitch bender with upward making notes sharp and downward bends making notes flat.
VCF switch- Determines how incoming pitch bender messages affect the lowpass filter (LPF) cutoff frequency. The highpass filter (HPF) is unaffected.
LFO- Pitch bender applies LFO modulation to filter cutoff frequency. Upward bends adds positive modulation; downward bends add negative modulation.
Off- VCF mod disabled.
Bend- Upward bends opens filter cutoff frequency; downward bends add negative modulation.
VCA switch- Determines how incoming pitch bender messages affect the lowpass filter (LPF) cutoff frequency. The highpass filter (HPF) is unaffected.
LFO- Pitch bender applies LFO modulation to amplitude. Upward bends adds positive modulation; downward bends add negative modulation.
Off- VCA mod disabled.
Bend- Upward bends increase overall amplitude; downward bends decrease overall amplitude.
Portamento On/Off and Speed knob- Also known as glide, Portamento causes notes to slide smoothly from one pitch to the next. Toggling the switch enables Portamento, and the Speed knob slows glide speed as it's increased. Portamento works in all voice modes; if you'd like to use it polyphonically, it works best (i.e., most predictable) in Poly 2 mode.
Transpose- Transposes the pitch of the entire instrument up or down one octave.