13. What is a command given to a computer to perfoillap 14. An ISA uses 5 bits for its opcode - how many unique operations can it perform? 15. Of the three stages in the fetch-decode-execute cycle, data storage usually happens in which stage? 16. What are the major components of a CPU (be brief and precise)? 17. Why do we need a system clock? 18. What is the purpose of the address/data registers? 19. What are two major types of ISAs? 20. What is the value of X if the register values are given as below? PUSH A; PUSH B ADD; PUSH D; MUL; PUSH E PUSH F SUB; DIV: POP X