A few Tips on the 303;s in Protrekkr....
Firstly there is a 3 octave range & if You try to go past those 3 octaves up or down it will simply 'clip' to the highest 'C' or Lowest 'C'...

Also here is a legend image from ReBirth's manual...Programming very similar-

Probably what you'll wanna do is use the 3100 (for bank one) or 3200 (for bank two) then push pattern play which will just keep repeating the pattern you are working on...Since you are only working up to 16 steps it works pretty well...
For Protrekkr itself I use what I call tactical composing....I don't fill in a whole shittin' pattern because then it would all sound too repetitive and mechanical and boring...
I put in 2-4 notes of an instrument, this could also be chords on multi-note lanes...Then I play & repeat several times whilst composing 'In The Head' to see where to go NEXT...
Mostly moving on in the solo type tracks but by using this method you can sometimes implement former ideas to fit in again...Like to mimic a certain style of play...
For instance if you have listened to Enigmatic303v21.mp3 you will notice in 3 spots there is a quick 'double-tap' of the exact same chord in the DX7-EP Rhodes solo...
I did not plan on doing that but by using such method I was able to re-use that idea for a 'fit' as originally I only had ONE 'double-tap'...Using tactical composing is slower but the outcome is usually much better than racing through like a jackrabbit then going back & applying 'filter sweeps' over the whole thing....
BTW...You PROBABLY think I am jamming out on some MIDI Controller...NOPE!...Yeah, I have 2 of them but I am doing that tune using just...JUST QWERTY...You see, it doesn't matter to me I am a CRAPPY realtime keyboard player...