Why would a guitarist want to know about MIDI?

So let me give you the rundown! Historically the Musicical Instrument Digital Interface, or MIDI, got started with MIDI keyboards. Although there were researchers and hobbiests experiementing with other MIDI devices including guitars, it was predominantly a keyboard world.

If you used a keyboard standalone (or without a PC), the MIDI keyboard MIDI out would be connected to the MIDI in of a sound module or other keyboard. The keyboard could then be used to play multiple sound modules at the same time. If you used a MIDI keyboard with your PC, a MIDI keyboard MIDI out would be connected to your PC's MIDI in. The PC's MIDI out would be connected to the keyboard's MIDI in. When you press a key on the MIDI keyboard the MIDI note number and velocity (how hard you hit the key) is transmitted over the MIDI. This is somewhat like an old piano-roll piano. If you've ever examined one, you know the holes in the roll let a pin slip through as the paper rolls by (with the speed that the roll is turning controlling the tempo). And the pin corresponds to the piano key that will be hit at a particular time (relative to the start of the roll). MIDI data is like this except it also includes some dynamics (i.e. how hard the key was hit). When the keyboard is operated "standalone", normally the MIDI out just loops back to the MIDI in. This is done internally so you don't need to put a MIDI cable in. Most MIDI keyboards let you turn off this automatic loopback when you're working with a PC so that you don't get double notes from the keyboard and from the PC echoing it back. It's as if the keyboard and sounds are two separate pieces. There's an assumption here. The PC must have some software directing the MIDI connectors on the PC for this to happen. That software is usually a MIDI sequencer which functions almost like a multi-track analog recorder. With the MIDI sequencer running, you start the record function and the sequencer program will store all the MIDI notes it receives into memory (and let you file them to disk later into a MIDI file). The recorded MIDI file can be examined with a graph showing the notes (and it looks almost exactly like a piano-roll). Most sequencer software is smart enough to display (and print) in standard musical notation as well. Cool!

There are a couple more wrinkles, but good ones. In addition to MIDI note number and velocity, there's a channel associated with MIDI transmissions. MIDI allow up to 16 different channels over the cable "simultaneously" (in quotes because I'm fibbing a little). Just like the cable TV coming into your house has 50 or 500 channels at the same time you can set a MIDI device to send or receive on a specific channel and it will only send or respond to notes for its channel. But you may have a TV with a preview capability that shows a whole bunch of TV channels at once so you can surf channels. Well some MIDI devices are like this. Actually most MIDI devices are like that these days. They can handle multiple channels at one time. Which is to say the MIDI device can "play" multiple instruments at the same time by being able to listen to multiple MIDI channels and play the notes for which each instrument is assigned. This assignment can be done on the MIDI device's panel or sometimes by using a computer program running on the PC. This way you can have a whole band in one keyboard -- piano, bass, percussion, vibes, flute, etc. As a general rule, as the number of instruments and/or simultaneous notes the keyboard can play increases, so does the price! And some MIDI keyboards have the squencer built in so you don't even need the PC. More information about MIDI here: www.students.sonoma.edu

List of sequencers (some freeware or at least free trials) below:

• www.sonicspot.com
• www.synthzone.com
• www.hitsquad.com
• www.brothersoft.com
• www.freedownloadscenter.com

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