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An Overview of MIDI

MIDI is a specification developed to allow computers and electronic
musical instruments to communicate with each other. Physical MIDI
hookups can get rather complicated; here is a brief primer:

MIDI hookups are a lot like your stereo, in that each device has IN
and OUT ports. However, MIDI devices also have a port known as THRU,
which retransmits information from the In port (more on why this is a
Good Thing later). MIDI devices are thus connected in a modfified
daisy-chain arrangement, with the Out of the master (usually a
computer) connected to the In of Slave #1, and Slave #1's Thru
connected to Slave #2's In, and so on. The Outs of all devices go to
the In of the master.

Here is a diagram of a simple hookup:

-----------------------------------
|----------------|
||___________|-----|
|||| ||||
In In OutIn Out ThruIn Out Thru
ComputerSynthDrum Machine
(Master)(Slave #1)(Slave #2)

MIDI is based on 16 'channels'.
Each channel is typically assigned to one specific device you have
connected in your chain. In the example above, you might have the
synth set to listen to channels 1-9, and the drum machine set to
listen to channel 10 (this is a typical assignment). With this setup,
when the computer transmits a note on channel 10, it will first go to
the IN of the synth, which will simultaneously retransmit it via it's
THRU port and notice that it doesn't want to use the data. The note
will then appear on the drum machine's IN port. The drum machine will
transmit it on it's THRU port (to which nothing is connected in the
example) and start the note. This allows flexibility; if for instance
you wanted you could connect a second drum machine with different
sounds, set it to channel 10 also, and have a unique mix :)

I will not cover MIDI recording and editing here, because there isn't
really any good MIDI software on the IIgs to cover. That's life.

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