For the record: source code for io 0.0.1 beta (rev. July 3rd 2004) [91kB zip file] and supporting components [198kB zip file]. Note that I have not differentiated components used by io and those that are not; I have included every file from the MyTools folder. Significant revisions since io 0.0.1 beta as detailed below.

From io:io_hp

 MOD: HeP 03-19-04 First experiments with floating point calculations.
 MOD: HeP 03-21-04 Speedup floating point code. Old floating point would drag
                   the system by 30% (35 ticks or so instead of the 26 ticks
                   set by hp_dur). New code gets us back to speed.

From io:io_input

 MOD: HeP 03-21-04 Use return stack version of CONFIGURE.BANALYZER.
                   Working version of POLY.DENSITY.FUNC using the updated
                   polyphonic parser classes. Experiment with calling these
                   during note on or off.
 MOD: HeP 03-21-04 Experiments with revised pulse.tracker.

From io:io_output

 MOD: HeP 03-23-04 Experimental changes to IO.DUR.FUNC.
 MOD: HeP 03-24-04 Players EXECUTE: ALERT-MATRIX less often (the use of
                   ob.fpgravity means that io's chaos is "smoother" and we
                   don't need that extra interest injection).
 MOD: HeP 04-09-04 Set instrument/channel volume via the PUT.VOLUME: method.
                   FADE.OUT also uses the PUT.VOLUME: method.
 MOD: HeP 04-11-04 Current reverb and pan settings are stored in variables.
                   The reverb enable/bypass is done via the instrument's
                   open function.
                   Set device id# for MIDI output.
 MOD: HeP 05-19-04 Experimental "muti-tasking" version of FADE.OUT which
                   keeps output activity alive while executing the fade.
                   See modules:io_interp.
 MOD: HeP 05-23-04 The new version of FADE.OUT (in modules:io_interp) results
                   in having to reset channel volume in IO.OUTPUT.STANDBY
                   instead of at end of IO.OUTPUT.STOP.