need some help with assembly. motorola 68k and M68230 PI/T (parallel interface/timer)

theres an exercise i have for uni, controlling a DC motor with the motorola 68k and 68230 PI/T.

i wonder if anyone could help me. i actually have the code but i cant understand whats it does exactly in some parts. so if anyone has any experience it would be very appreciated. i first need to know if anyone could help before i post the long explanation of the whole thing and how it works.