JI in MIDI

I compose for MIDI using James Allwright's abc2midi DOS utility
(http://perun.hscs.wmin.ac.uk/~jra/abcMIDI/), and I'm tired of being
limited to the 12-tone ET scale. I'm new to MIDI composing and also to
alternate tunings. What I'd like to do is redefine some pitches, like
making C exactly 264 Hz, E exactly 330 Hz, etc. How can I do this? Is
there a good place on the Web that explains this type of thing? The
abc2midi program is all I have to work with.

Also, is there a Web resource that comprehensively explains the terms
otonal and utonal?

--
Rob LeGrand
honky98@aggies.org
http://www.aggies.org/honky98/midi.html

>Also, is there a Web resource that comprehensively explains the terms
>otonal and utonal?

Unfortunately, Partch's glossary definitions (reproduced in Monz's
dictionary) are pretty useless. It's pretty simple, though. Here are some
frequency ratios for otonal chords and their utonal counterparts:

otonal utonal
4:5:6 1/6:1/5:1/4=10:12:15
6:7:9 1/9:1/7:1/6=14:18:21
16:19:24 1/24:1/19:1/16=38:48:57

Otonal chords are best though of as overtones over a (possibly absent but
often still audible) fundamental, while utonal chords are best thought of as
a set of fundamentals with a single common overtone (called the guide tone).
For example, 4:5:6 is the 4th, 5th, and 6th harmonics of 1, while
1/6:1/5:1/4 has a guide tone of 1 which is the 6th harmonic of the first
note, the 5th harmonic of the second note, and the 4th harmonic of the third
note. Clearly, your tones need to have integer harmonics for utonal chords
to "work", while otonal chords will "work" even if you have no harmonics at
all or even a mild set of inharmonic partials.