4. ABOUT MIDI
MIDI stands for Musical Instrument Digital Interface. MIDI is a world-wide standard that
allows musical instruments and computers to exchange musical data. Most electronic
musical instruments sold today are MIDI compatible. MIDI compatible devices have
MIDI connectors which are used to physically link instruments (using special cables).
MIDI does not transmit the sound of an instrument, but rather ‘messages’ in digital form
that tell the receiving instrument to “do something.” These are known as MIDI messages.
(1) MIDI Message Exchange
How the exchange of MIDI messages is carried out is explained in the following.
MIDI Connectors
In carrying out the exchange of MIDI messages, three connectors are used. MIDI cables
are connected to these connectors in various ways depending on the desired result:
MIDI Channels and Multi-Timbral Capabilities
With MIDI, a single cable can be used for carrying differing sets of performance informa-
tion, for a number of MIDI devices. This is possible thanks to the concept of MIDI chan-
nels. MIDI channels are easy to understand if we use the analogy of television broad-
casting.
Many television programs are broadcast from many TV stations and your TV antenna
receives them all. By setting your television to a specific channel, you can watch only
the desired program. The same idea applies to MIDI channels. The master device is
somewhat like the broadcast station, and the slave device is like a television receiver.
The MIDI messages carried by the MIDI cable are like the programs that are transmitted
from the broadcast stations.
OUT
THRU
M I D I
IN
Station A
The cable from the antenna carries the TV signals for a variety of broadcasts.
On a TV, the channel is selected
to watch the station you want.
Station B
Station C
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MIDI IN connector:
This connector receives incoming MIDI messages.
MIDI OUT connector:
This connector transmits outgoing MIDI messages
to other devices.
MIDI THRU connector:
MIDI messages received at MIDI IN are re-trans-
mitted by the MIDI THRU connector. (This con-
nector does not transmit messages that originate
inside the unit itself.)
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