SynthModules

It's working!!!

I was bound and determined to figure out the occasional glitches with
the interrupt-driven MIDI input.  I'm used to assembly language
stack-based machines.  I was using the same variables in the
interrupt service routine so I had problems with stepping on the
variables in the main code during an interrupt.  I had to change to
local variables where possible in the interrupt service routine and
disable interrupts in the main code when checking or manipulating
these variables.  This also corrects the issue I was having with byte
variables. For some reason setting the variables to words greatly
reduced the frequency of collision.

I merged the polled and interrupt modes with a compile option.  You
can compile for either polled MIDI input or interrupt MIDI input. 
The MIDI output is always polled.

I'll upload the code later tonight.

Dave