position = mem.position
if position == nil then
	position = 0
end
position = position + 1
if position > num_of_notes then
	position = 1
end
mem.position = position

if pin.b then
	if notes[position] == nil then
		port = {a=false, b=false, c=false, d=false}
	elseif note[position] == 1 then
		port = {a=true, b=false, c=false, d=false}
	elseif note[position] == 2 then
		port = {a=false, b=true, c=false, d=false}
	elseif note[position] == 3 then
		port = {a=false, b=false, c=true, d=false}
	elseif note[position] == 1 then
		port = {a=false, b=false, c=false, d=true}
	end
else
	mem.position = 0
end