MIDI Basics

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What is MIDI?
MIDI Messages
  System Exclusive
Electrical Overview
Basic MIDI Set-up
Channels and Tracks
Patches and Programs

What is MIDI?
The Musical Instrument Digital Interface. It is a way to send instructions ("messages") between instruments. MIDI is NOT audio or digitized audio signals (like wave files).

MIDI (pronounced "mid-ee") is a "standard", meaning the electrical specifications and messages have been defined and published. Anyone making MIDI equipment should follow this standard if that equipment is to work with equipment from other manufacturers.

MIDI Messages
A typical MIDI message is "Play middle C". MIDI terminology for "play" is "Note On". The MIDI standard has assigned a number to each key on the keyboard. Middle C is number 60, so the MIDI way of saying "Play middle C" is "Note On 60". (To see a web page of MIDI Note Numbers for the 01, click here.)

Notice the "format" of the MIDI instruction: "What to do" (Note On)  is followed by "where to do it" (note number 60). In general, MIDI instructions follow this format.

To make things faster and more efficient, each MIDI instruction have been assigned a unique number. For example, Note On is number 9. There are lots of other instructions and lots of other numbers, and it all gets quite complicated. The point is: MIDI is messages that are represented by numbers.

MIDI messages that a device can understand are supposed to be shown on a MIDI Implementation
Chart. To see the Chart for the 01, click here.

System Exclusive Messages
Each manufacturer wants their MIDI device to do something special that no other MIDI device can do exactly the same way. Rather than clutter the MIDI standard with thousands of messages that are exclusive to a single device, the MIDI standard defined a message type called System Exclusive.

A System Exclusive message has a standard beginning, saying "This is a SysEx message from manufacturer So-and-so". After that comes whatever manufacturer So-and-so wants. The message ends with a standard ending.

The idea is that all MIDI devices will read the start of the message. If a device isn't manufactured by So-and-so, it will ignore the rest of the message. For more details on 01 SysEx messages, click here.

Electrical Overview
The MIDI messages must get from one instrument or device to another, and that's where electricity comes in. MIDI message numbers are converted into binary (ones and zeros) so they can be sent over wires as voltages (1 = some volts, 0 = no volts).

Electronics circuits (microprocessors) arrange these binary messages in the proper sequence, then send them out over the MIDI cable you plug into your instrument or computer. Microprocessors on the receiving end take the stream of ones and zeros, figure out what the message is, then does what the message says.

Connecting MIDI Devices


There are three possible MIDI connections: MIDI OUT, MIDI IN, and MIDI THRU.

MIDI is 1-way data highway, just like water in a hose. Data flows out the MIDI OUT port and into some MIDI IN port. Knowing this, you now understand cables connect an OUT to an IN.

A typical computer connections:
MIDI Cable 1: Connect Computer MIDI OUT to 01 MIDI IN. This lets your computer play songs through the 01.
MIDI Cable 2: Connect 01 MIDI OUT  to computer MIDI IN. This lets your computer record what you play.

You don't use MIDI THRU in a basic system. MIDI THRU is an output which contains a copy of what appears at MIDI IN. Data going in the MIDI IN connector passes through the device and out MIDI THRU. MIDI THRU can work in either of two ways.

1. Strict MIDI THRU is an exact copy of what came in the MIDI IN port. It is not a simple wired connection - there is some electronic circuitry between the IN and THRU connectors.

2. Some devices (like the 01) will "merge" their own MIDI data with what came in the IN port, and then send it out the THRU port. In this case, THRU is a combination of IN and OUT.

01 & Software

Computer-based Sequencing

Note: In most cases, you will want the 01 to be in SEQuencer Mode, even if you are using an external sequencer. You should at lease start out this way until you know everything is working.

Put the 01 in SEQuencer mode. Page 0 shows there are 16 tracks. These exactly correspond to the 16 MIDI channels (until you change it). That is, Track 1 is connected to MIDI Channel 1, Track 2 = MIDI Channel 2, and so on. (For a discussion about Tracks and Channels, see below.)

Load your computer-based sequencer. You will probably see lots of blank tracks with no channel assignments. Your first task is to connect the first 16 tracks to the 16 MIDI channels. This should be as simple as putting the cursor in a box and typing a number. (Look for a column labeled "Chn" or something similar.)

If you connected the MIDI cables correctly (and your computer hardware and software are properly installed), things should work.

Click on "Record", play a few notes on the 01, then click "Stop". You should see some data show up in the sequencer. If you did not, check to make sure the MIDI cable is firmly connected from the 01 MIDI OUT to the computer's MIDI IN. If this looks good, you can try resetting your 01 to make sure all those settings are normal. Otherwise, check the computer hardware and software installation and settings (haul out the manuals or call technical support).

If you have notes in your sequencer, you can simply click on "Play" and hear the notes played back. They will probably sound "spacey". If you hear notes, then the MIDI connection for playback is okay. You can now change the 01 Program by going to the "Bank" and "Patch" boxes on your computer screen and changing those. As you enter new numbers, you should see the same number show up on the 01 LCD in the same track.

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Channels and Tracks

MIDI has channels. It does NOT have any tracks. More specifically, MIDI has only 16 channels.

Sequencers (and other recording devices like tape recorders) have Tracks. A computer-based sequencer can have hundreds of tracks. The 01 sequencer has only 16 tracks.

Technically, a Channel is an address. Typically, it's the address of a generic box. The box can hold one instrument ("patch" or "Prog", same thing), one volume setting, one pan setting, and so on. However, you can change any of these settings instantly. (Try getting a live musician to do that.)

What's a track? A place to record the notes (and other playing information), usually for one instrument. Much like one staff of written music.

So you have written music (tracks) and programmable music "boxes" (channels). If you want a track to be played, it has to be assigned a box to play through. Said a different way, every track has to be given a MIDI channel.

Patches and Programs
One music box can be only one instrument at a time. The first message you send to each box is which instrument to play. An instrument is usually called a "patch", but Korg calls it a "Program", or "Prog" for short. You can tell each box/channel different things, like how loud to play (volume) and where to play (pan).

1. A Channel is one instrument. A track is one staff of written music.
2. You can have several tracks for the same instrument/channel, BUT
3. Just one instrument per channel at a time. Different instruments/patches/Progs must be assigned to different Channels.

In 01/W terms, you have 16 tracks in the sequencer. You can assign one Prog to any of the tracks at any time - up to 16 Progs. Each Track can be assigned to any of the 16 Channels. (The 01 assigns Channels in SEQ Mode, Page 3/4, Line 2.) In a computer-based sequencer, there is a box to specify which channel that track goes out on. Different instruments go on different channels.

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Copyright ©1998-2002 by Ken Westover at Cliff Canyon Publishing Co. All rights reserved.
This material may not be distributed without the written permission of the author.
  E-mail questions or comments to cliffcan@indra.com.
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