Sorry as i say i am very new to this so I'm still not educated enough yet.. what is the 1/8/16/20mhz about and even for? I'm not sure but if that was to help by changing the clock then whats the procedure?
So what your basically saying is you believe theirs a chance the code is actually good enough to control variable resistors with the pins i have stated? but that the 84 is just not capable as of yet?
also you mention about a Crystal..... I don't follow? sorry for the noob questions...