Roland Octapad SPD-20X Owner's Manual page 56

The Note Numbers fall within the range of 0–127, with middle C (C4) as number 60.
Note numbers usually specify the pitch of the sound to be produced, but for rhythm sound generators,
they specify the type of drum sound (the Instrument) which is to be played.
With the SPD-20X, Note Numbers for transmitting and receiving are set with the MIDI parameter NOTE #.
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• Aftertouch messages
Aftertouch messages are transmitted by some keyboards when you press down on the keyboard
after playing a note. The degree of pressure (aftertouch) can thus be used to control various
aspects of the sound. There are two types of aftertouch messages. Data which is transmitted
independently for each key is called Polyphonic Key Pressure, and data which is transmitted for the
overall keyboard (without differentiating between individual keys) is called Channel Key Pressure.
The SPD-20X transmits Key AfterTouch messages when the rim area of a pad (CY-5, CY-8) is squeezed or
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released. When the SPD-20X receives Key AfterTouch messages from another MIDI device, its sound will be
affected in the same way as when the rim area of a pad is squeezed.
• Program Change messages (1–128)
These messages are usually used to select sounds.
The SPD-20X can transmit Program Change messages to select Patches on external sound modules . When
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the SPD-20X receives a Program Change message from another MIDI device, the Patch will change.
• Control Change messages
These messages convey various types of information that make a musical performance more expressive.
Each message carries a control number that indicates which function it is to control. The result will
depend on the MIDI device.
The SPD-20X transmits movements of the hi-hat control pedal as Control Change messages.
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When it receives Control Change messages from another MIDI device, its sound will be affected in the
same way as when the pedal is moved.
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