The MIDI specification includes a common language that provides information about events, such as note on and off, preset changes, sustain pedal, pitch bend, and timing information. The specification has been updated more recently with specific data structures for handling sample dumps, MIDI time code, general MIDI and standard MIDI files. The third pin is a ground and the remaining two pins are currently not in use. The MIDI data is sent down the cable one bit at a time as a stream of information, which is called a serial interface . A parallel interface allows the information to be sent down separate wires so that the message reaches the device at the same time, making it faster than a serial interface.
Computer chips communicate via a parallel interface.
The serial interface was chosen by MIDI manufacturers because it is less expensive and more efficient than a parallel interface. The speed of a MIDI serial interface is 31,250 bits per second . There are 10 bits needed for every MIDI digital word or 3125 messages per second . Snap your finger and think about how many many events could be transmitted during that time. Consequently, the serial interface speed is more than adequate for most music applications.