The following few machines are given informal descriptions. Decide whether they are of CISC or of RISC design, and provide a short description of why.

a) Machine A has over 300 instructions, many of which are executed at most once per program.

b) Processor B has only 50 machine instructions, and a general-purpose register bank.

c) Processor C has 15 different addressing schemes and four accumulator registers. Most of its instructions involve reading from memory directly into the accumulator. Most of its instructions have only one address, but the few that don't, take up fewer bits.

d) Processor D was designed specifically as a network-of-devices monitoring chip. It can read in data from memory (expected to be placed there by some device) and do simple math upon it in the same operation. However, it has less than 100 instructions, in a total of four formats, as there are a lot of features it's missing. (For example: all math operations are computed in a fixed width.)