Akai MPC 4000 Reference Manual page 89

Routing page
INT-B .....................Virtual MIDI port B of the sampler section
SEQUENCER ........The sequencer section
D Drum pad field
Selects one of the following as the destination of the MIDI events generated by the pads.
INT-A .....................Virtual MIDI port A of the sampler section
OUT-A....................MIDI OUT A
SEQUENCER ........The sequencer section
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