While MIDI voice messages are specific to a MIDI channel, system common and system real-time messages are not specific to a channel and thus all MIDI devices on the MIDI system should respond to such messages. Thus, these messages are "system" messages. Some of these system messages provide timing information and usually require that devices react in real time, and are called "system real-time" messages. The rest are "system common messages".
MIDI system common messages are those MIDI messages that prompt all devices on the MIDI system to respond (are not specific to a MIDI channel), but do not require an immediate response from the receiving MIDI devices.
The following messages are MIDI system common messages.
|Message||MIDI device action|
|System exclusive (sysex)||Perform some device specific action|
|Quarter frame||Understand the MIDI time to keep in line with some other device|
|Song position pointer||Cue to a point in the MIDI sequence to be ready to play|
|Song request (song select)||Set a sequence for playback|