Appendix F: Midi 101 - Peavey PC1600X User Manual

Appendix F
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MIDI 101:
When most of us use MIDI, the actual messages that move through the MIDI cable are often of little
concern. After all, we are too busy making music to be bothered with such technical things. However,
occasionally, it becomes necessary to work with MIDI messages and, therefore, it is handy to understand
how they work and how to use them.
Let's look at four types of MIDI messages:
Channel Messages
System Exclusive Messages
System Common Messages
System Real-Time Messages
But first . . .
MIDI messages are displayed using hexadecimal notation (see Hex article on page 30. Getting a basic
handle on this numbering system is half the trick in working with MIDI messages.
Channel Messages
Let's take a look at channel messages. These are so-named due to the fact that the MIDI channel is
imbedded into the message itself. The receiving MIDI device must be set to the same channel or the
message will be ignored. Channel messages are either two or three bytes in length with the first byte being
the status byte. This signifies the message type and MIDI channel. The byes that follow are known as data
bytes and contain the actual value of the message. Let's take a look at channel messages (n-MIDI channel,
x=value)
System Exclusive Messages
SysEx (System Exclusive) messages "speak" to specific synthesizers, sound modules, or other MIDI devices.
That is why they are referred to as "exclusive" messages. For example, if SysEx messages for the Spectrum
Synth are sent to the Spectrum Organ, the module will ignore the messages. Only the Spectrum Synth will
respond to Spectrum Synth SysEx messages.
All SysEx messages start with F0 ("Start of SysEx" message), and end with F7 ("End of SysEx" message).
The anatomy of a typical message is as follows:
SysEx messages are used to edit parameters on a MIDI device, remotely, yet in real time. Devices such as
the PC 1600 can be programmed to transmit SysEx (and other) MIDI messages using faders, buttons, pedals,
and a data wheel.
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Peavey PC1600X User Manual (rev-h)