eral Questions: (a) What does GPIO stand for and what is its purpose? (b) Most GPIO interfaces allow alternative functions for each pin they represent. Give an example of an alternative function for a GPIO pin. (c) What is the difference between microcode and machine code? Be very specific and use diagrams if that helps your explanation. (d) List all registers used in the ARM architecture and describe their overall purpose. Include in this description the standard uses for function calls. Just listing the registers will only get you half credit. within its code, how do you handle returning back to the calling routine? In other words, how do you preserve the return address for the first call? (e) If you are writing a subroutine in assembly language that calls a second subroutine