The exception to this is OMNI mode. An instrument set to receive in OMNI mode will accept and respond to all channel messages, regardless of the channel number. The note will sound until a message to turn off the same note number is received. Simultaneous events in MIDI must be sent as a string of serial commands. Because of the 31 Kbaud transmission speed, this is normally perceived as a simultaneity.
Many instruments transmit and respond to key velocity, the speed at which a key is depressed.
Most simply allow dynamic range to be controlled, while others have the capability to alter timbre or spatial location through velocity. Return to Index System Messages System Message codes are addressed to all instruments and devices regardless of their channel assignments. SysEx codes allow storage of large amounts of patch data, the standard recallable unit by which synthesizers store their sounds. In many cases SysEx software has added extremely useful graphic representations of patch parameters not available from the limited LCD's on most instruments. It has also allowed the computer to generate its own patchs, randomly or algorithmically.