System Messages; Running Status - Classic Organ Works CMK-1 User Manual

Channel Mode messages affect the way in which a synthesizer responds to MIDI data. Controller number 121
represents a reset. Channel number 122 represents an enable/disable local control. Channel numbers 124-127
select whether a synthesizer responds to MIDI data on all channels or on one channel only (Omni Mode On or
Omni Mode Off). The notes are then played polyphonically or monophonically (Poly Mode and Mono Mode)
respectively.

System Messages

These are messages which are not Channel specific, and thus do not indicate the channel number in their status bytes.
System Common Messages serve to synchronize MIDI equipment (MIDI Time code), select songs (for MIDI
equipment with the capability to store and recall a number of different songs), select the playback point (for
MIDI equipment with MIDI system real time message recognition), tune internal oscillators, and flag the end
of a System Exclusive Message.
System Real Time Messages are used to set the playback tempo (timing clock), control the playback start
position (start), continue playback (continue), set the stop position (stop), eliminate 'stuck notes' (active
sensing) in the event of a MIDI cable disconnection, and reset and initialize the equipment receiving a message
(system reset).
System Exclusive Messages are specific to a manufacturer. Each manufacturer of MIDI equipment is granted
a unique identification number by the MIDI Manufacturers association which is the first byte of the message.
Afterwards, a manufacturer can send data and patch commands.

Running Status

In addition to the messages sent between MIDI devices, the MIDI language has a 'Running Status' feature which
eliminates the delayed effect caused by a large number of musical events occurring 'simultaneously'. The Running
Status does this by omitting the status byte if the current status byte is the same as the previous status byte. So, one
less byte is sent which will vacate that byte for other data. Often, to make use of the Running Status feature, the 'Note
On' message is utilized for both 'Note on' and 'Note off' functions. Since the 'Note On' and 'Note Off' messages
have differing status bytes, by making use of a 'velocity = 0' command in place of the 'Note Off' command, running
status is utilized.
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CMK-1 Manual (Issue-1)
Page-57
October 20, 2004