Re: what is (MIDI /Musical Instrument Digital Interface)????
MIDI also allows multiple MIDI-capable devices (which are easily identified by having a MIDI port) to control or be controlled by a single MIDI-capable device.
For example, the ART X-15 Ultrafoot pedalboard from way back in the late 80s was this huge foot controller that had two treadles and 12 buttons. While Digitech's foot controllers for their rack units would only work with their own gear, and usually only the item it was built for, like the GSP 21, the ART X-15 worked with anything made by anyone, as long as it had a MIDI port and could receive the standardized commands of the General MIDI specification, such as Program Change (i.e. switching Presets), Note Number (where a MIDI Note is directly linked to a Keyboard note, meaning MIDI Note C# played a C# on your digital piano or synth unit), Tempo Up/Down (usually for drum machines, but later included Digital Delay units), Start/Stop commands for sequencers, and Continuous Controller commands for things like Volume and Pitch controls found on most synths, and later in Rack units which had either a Volume control or a Volume Pedal or Wah pedal.
If you had multiple rack units with MIDI capability - Compressor, Drive, Delay, Reverb, Chorus, etc etc - you could connect them all to each other with MIDI cables and control patch changes on all of them at once using just one controller. Some amps even feature MIDI-controlled channel switching, so if you had effects that were only used when you switched to the Crunch channel, turning that effect on would automatically switch to that amp channel, and turning it off would switch back. Alternatively, changing the amp channel would turn said effect on, while switching back would turn it off.
A lot depends on which unit you set as the controller and which one is to be controlled. You may, for example, want to use the Crunch channel without that one effect, or use that effect with the Clean channel. In that event, you want it set so changing amp channels turns the effect on/off, rather than turning the effect on/off changes amp channels.
As well, a MIDI-based desktop mixer can control your Digital Audio Workstation on your PC, which makes adjustments faster and easier than chasing things down with a mouse individually. You turn a knob or slide a fader on the mixer and that data is passed to the DAW, though I'm sure more recent mixers do all that through USB directly.
