Which of the following is suitable as a description of the microprogramming control method?
a) It is used on many RISC processors.
b) Functions can be added and changed just by making microprogram changes, so it is easy to add and change instructions.
c) Like ordinary programs, microprograms are stored in main memory, and read and used by processors.
d) Machine instruction processing is faster than in the case of the wired logic method.