You can read about how the OT responds to incoming MIDI notes on page C-1 of its manual.
Basically, the OT will play samples on audio tracks chromatically when receiving notes that are within one octave of MIDI note number 84. So you can only use MIDI note numbers 72 to 96 to play chromatically.
The OT responds to other MIDI notes by trigging tracks or samples or by changing its status.