Dave,

There's a bit of a problem with this section
Code:
If porta.0 = 0 Then sw1on ' check sustain pedal
If porta.0 = 1 Then sw1off 
If porta.1 = 0 Then sw2on ' check portamento pedal
If porta.1 = 1 Then sw2off

If porta.2 = 0 Then 
Hserout [255] ' reset all controllers
Endif

Goto Loop ' go back to continuous monitoring

sw1on:
If sw1 = 0 Then ' check to see if sustain is off
sw1 = 127
Hserout [176,64,sw1] ' turn on sustain
Endif

sw1off:
If sw1 = 127 Then ' check to see if sustain is on
sw1 = 0
Hserout [176,64,sw1] ' turn off sustain
Endif

sw2on:
If sw2 = 0 Then ' check to see if portamento is off
sw2 = 127
Hserout [176,65,sw2] ' turn on portamento
Endif

sw2off:
If sw2 = 127 Then ' check to see if portamento is on
sw2 = 0
Hserout [176,65,sw2] ' turn off portamento
Endif
If porta.0 = 1 the program will GOTO sw1off. It will then proceed to sw2on, sw2off and finally go off into LaLa land as there's no way to go back to the main Loop. The last thing you'll see before it dies is the portamento command (assuming conditions are right)

You could changed each of the sw1on: sw1off: sw2on: sw2off: sections to a subroutine ending with RETURN. Then, for the tests...

If porta.0 = 0 Then GOSUB sw1on ' check sustain pedal


Best regards,
   Darrel