What is MIDI?

MIDI stands for Musical Instrument Digital Interface MIDI is a communications standard; as its name suggests, it was designed as a "Digital Interface" (for you non-techies, this basically means that binary 0's and 1's are being sent over a wire from one device to another) for "Musical Instruments".

MIDI was born in 1983 when a group of major electronic-instrument manufacturers realized the need for such a standard and developed one. Before MIDI, it was very difficult or impossible to interface equipment made by different manufactures. Therefore, it was quite common to see keyboardists playing several keyboards at the same time, since no one keyboard was the "overall best" in everything.

Physically, MIDI consists of three wires with a five-pin DIN type connector at each end (two pins are not used). The connectors look a bit like the background of this page, as well as other graphics on "Twin Cities MIDI".

MIDI data is not the same as sound data. What is transmitted over the wire is information on how to play a song, not the physical sound data itself. MIDI can be thought of better as a player-piano roll than a compact disk: just as the piano-roll instructs the player-piano to create the sounds, MIDI data tells a MIDI device which notes to play, patches (instruments) to use, and other information to help the instrument recreate the song. When you listen to a MIDI file, you're hearing an actual 'performance' by the instrument, not a 'recording' of a past performance.

MIDI was not designed to be used with personal computers, but since it is a digital interface, they actually work very well together. Combining at least one MIDI instrument with a personal computer and a MIDI interface (a device that allows the computer to "speak" MIDI) allows for many interesting applications. With a music notation software, such as Coda Music Technology's  Finale, music can be played on a music keyboard or other MIDI instrument, and immediately be displayed on the computer screen. Mistakes can be corrected, and other musical symbols, such as dynamic markings, tempo changes, and even lyrics, can be entered to make a complete score. In effect, you have a music "word processor", and the advantages parallel those of using a word processor over a typewriter. Another very popular piece of software is the MIDI sequencer. This software allows musicians to create songs one "track" at a time, similar to a multi-track tape player, using a MIDI device. The difference is the sequencer doesn't record the sound but the actual "notes" and other MIDI information. Therefore, if a performer makes a few mistakes in an otherwise great performance, s/he can correct the wrong notes via the computer and all is well!

Technically, there is no such thing as a "MIDI file", but you'll hear the term all the time, including right here on Twin Cities MIDI. What is really meant is a Standard MIDI File, or SMF. This file is a computer-independent standard for storing MIDI data in a computer file. Although most MIDI programs have their own formats for storing things, virtually all of them can speak SMF, allowing basic MIDI data to be transferred from program to program (at the risk of losing some specialized data from the individual program).

Recently, General MIDI has appeared as a new addition to the MIDI standard. General MIDI adds standards on the order of patches (instruments), such as Acoustic Piano being #1, etc. It also standardizes drum kits, that is, which notes play which drums. Non General-MIDI keyboards can do what they want with these orderings, making it difficult to play sequences done on one instrument on another one (a "remapping" is required. Most of the files you'll see on the Internet are General MIDI.

Although MIDI was designed for the professional musician, it is quickly becoming available to the average computer user. Many PC soundcards, such as certain SoundBlasters and the GUS Ultrasound, contain MIDI capability. For Macintosh users, QuickTime 3.0 contains a built-in MIDI capability (see the TCM Mac MIDI page for more information). With most of these computer-only solutions, the sound quality suffers over a "real" MIDI instrument, and some setups do not contain MIDI jacks, therefore losing the advantage of MIDI keyboard input. However, for the casual user it is probably good enough. The next level up would be to buy a low cost General MIDI device which contains a built in MIDI interface. For example, the Yamaha CBX-T3 contains 192 voices plus drums, a built in MIDI interface which hooks directly to your computer, and MIDI IN/OUT/THRU jacks for adding additional instruments. In general, the sound quality will be much better than a computer-only solution. However, it also lacks a keyboard for music input, but one may be added using the MIDI jacks. For the more advanced user, many, many very good instruments are available from the hundreds to the thousands of dollars.

The Goldsmith College Electronic Music Studio page has links to several decent introductory MIDI articles and help for Mac users. Click on the links button.

Tutorial on MIDI and Music Synthesis does an excellent job of explaining MIDI and has excellent drawings that show how to connect MIDI equipment to computers and how to connect MIDI devices together to create a complete MIDI system.

Back in 1992 when he was an undergrad, Tim wrote a paper on computer music. It's a bit outdated and basic, but some might still find it useful.

A MIDI Primer by Tom Parker has lots of very good MIDI information.

For more information about the MIDI specification read the MIDI Primer.

Frequently Asked Questions

Question: Where can I find MIDI cables?

Answer: You can make your own with parts from Radio Shack following instructions found on the Web or you can buy them from a music store that sells MIDI devices.  I have found that the 5 pin DIN audio cables sold at Radio Shack work well for me when I need short cables. (Try at your own risk).

Question: How do I connect my MIDI Keyboard to my Macintosh?

Answer: You used to be able purchase a MIDI adapter from Apple Computer a little box with a 5 pin DIN MIDI IN and 5 pin DIN MIDI OUT connector that connects to your printer or modem serial port (or both) via an 8 pin mini DIN cable. These were about $90 when I purchased mine 8 years ago. I replaced them with a device that is called a Opcode Studio 3 that allowed me easily switch between MIDI, modem and printers. I don't know if Studio 3's or Studio 5's are still available but I have seen advertisements for a Opcode Studio 64x on the Web that does the pretty much the same thing plus more and can be used on a PC serial port as well. If you have a Yamaha CBX-T3 or a Roland SC-88 connected to your MAC you can use the MIDI jacks on them (I think).

Question: How do I connect my MIDI Keyboard to my PC?

Answer: You can buy a Roland MPU-401 MIDI Card or equivalent (If they are still available). You can use a sound card that has a MPU-401 chip. If you have a Yamaha CBX-T3 or a Roland SC-88 connected to your PC's serial port you can use the MIDI jacks on them (I think).

Question: Which end of what cable goes where?

Answer: Once you have some sort of MIDI interface installed, such as a sound card with a MIDI adapter cable, you need to know that the keyboard MIDI OUT goes to the interface MIDI IN and the keyboard MIDI IN goes to the interface MIDI OUT.  The same holds true of any two MIDI devices you connect together.

The more pictorial view below may help:

Keyboard MIDI OUT ----- cable -----> Computer MIDI IN

Keyboard MIDI IN <----- cable ----- Computer MIDI OUT

Keyboard MIDI THRU ----- cable -----> Drum Machine MIDI IN

Some devices may not have a MIDI OUT. These are intended to accept MIDI data but not to send it.  Likewise some devices only have MIDI OUT and are intended to send MIDI data but not receive it.

Question: My sound card has a MPU-401 chip but does not have the 5 pin DIN MIDI IN and MIDI OUT jacks. Where do I connect my MIDI cables?

Answer: I have never seen a sound card that was packaged with a MIDI adapter cable. I purchased my first one by calling Creative Computing and ordering it by phone. The last one I bought is made by Advanced Gravis and I found it at Computer City. The last time I looked for one I found out that unfortunately Advanced Gravis was no longer in the sound card business.  My advice is to call your sound card manufacture first before investing in one of these packages just to get cables. Midisoft also has just the Universal MIDI Cables according to their web site. The MIDI adapter cable connects to the joystick port and split it into 2 joystick jacks, a MIDI IN, a MIDI OUT and a MIDI THRU. There are instructions that can be found on the Web for building your own but that's for braver and more determined "techies" than me.

Question: Can I work with MIDI without understanding anything about the MIDI Specification?

Answer: Yes, especially if all you are doing is using a a PC sound card or a single external synthesizer, but if you plan on purchasing or connecting several MIDI devices together such as drum machines, keyboards, samplers and the like, it would be wise to at least  learn enough so that you can understand the MIDI implementation chart that comes with every (non-computer) MIDI device.  For example, some of the cheaper keyboards (low end Yamaha and Casio) available do not implement velocity. If you care about being able to control and represent the loudness of each note as it is played this is important!

Twin Cities MIDI Home Page