(b) write a de to generate 2. A processor has an external input clock of 15MHz, It is required that the system clock (Fosc) be Fosc=60MHz. (a) If it is required to start with the cheapest and most efficient oscillator source (S0..S7), which one will it be? (b) Which clock source are you going to switch to if you want to boot up the frequency and why? (c) What are the values of the configuration registers FOSCSEL.NOSC and FOSC.POSCMD in binary? (d) Determine the valid settings which have the minimum value for N1, M, and N2. (e) Write a code that sets configuration registers and SFR required to switch to the desired system clock.