2. Let's assume that there are three processors, Pa, Pb, and Pc, that support different ISAS. Note, you can assume that l-way superscalar, no hyper-threading, and no pipeline for all processors. Pa: 4.2 GHZ clock rate, CPI: 2.1, ISA: A Pb: 2.5 GHZ clock rate, CPI: 1.2, ISA: B Pc: 3.5 GHz clock rate, CPI: 1.7, ISA: C 2.1. (15 points) Assume that you write a program using an assembly language for Pa. Can the program run on Pb and Pc? Explain your answer. 2.2. (15 points) Assume that you write two programs, hello.c and goodbye.java. Explain how these programs can run on these CPUs. 2.3. (20 points) Find a CPU that executes the most number of instructions per second. 2.4. (20 points) Can you conclude that the CPU you found in 2.3 provides better performance than other CPUs in terms of "execution time per program"? Explain your