19. (a) What does the following code do? EQU Sae LDAA SWIT ANDA #$10 BEQ LOOP1 SWIT: LOOP1: A. B. C. D. E. Waits for bit 3 to go low Waits for bit 3 to go high Waits for bit 4 to go low Waits for bit 4 to go high None of the above (b). Reduce them to one instruction 20. Assuming an 8-MHz crystal frequency is used, what is the approximate number N in order to delay 10 milliseconds? LDX #N DEX BNE DELAY ;2 cycles 1 cycle ;4 (back)/2 (down) cycle(s) DELAY: 21. Program for reading keypads 22. What pieces of information are typically placed in a Stack? For each piece of information, what is its purpose of storing in a Stack? 19. (a) What does the following code do? EQU Sae LDAA SWIT ANDA #$10 BEQ LOOP1 SWIT: LOOP1: A. B. C. D. E. Waits for bit 3 to go low Waits for bit 3 to go high Waits for bit 4 to go low Waits for bit 4 to go high None of the above (b). Reduce them to one instruction 20. Assuming an 8-MHz crystal frequency is used, what is the approximate number N in order to delay 10 milliseconds? LDX #N DEX BNE DELAY ;2 cycles 1 cycle ;4 (back)/2 (down) cycle(s) DELAY: 21. Program for reading keypads 22. What pieces of information are typically placed in a Stack? For each piece of information, what is its purpose of storing in a Stack