For the 1st - 428th prime numbers the tones are determined the same way as the 1st part. It then pauses while the 3rd part executes.
When the 3rd part is done, the 2nd part does the same using the 569th - 1002nd prime numbers in the following way:
Start at F, 1 means descend a scale step, 2 means ascend a scale step (there are no zeros). When done, double the 3rd part to the end.