Which architecture uses a small set of simple instructions?

• A. Complex Instruction Set Computing (CISC)
• B. Reduced Instruction Set Computing (RISC)
• C. Instruction Set Architecture (ISA)
• D. Operating System

Answer: (B)

A processor design that uses a small set of simple instructions aims for fast, predictable execution and easy pipelining. This Reduced Instruction Set Computing approach sticks to a limited, straightforward set of operations with typically fixed-length instructions, so the control unit can decode and execute each instruction quickly in a uniform way. The simplicity helps the hardware implement efficient pipelining and consistent timing, which often translates to high performance in practice.

In contrast, architectures with a Complex Instruction Set Computing philosophy rely on a larger and more varied set of instructions, many capable of performing multiple tasks in a single, more powerful operation. This can reduce code size but makes decoding and pipeline design more challenging, since instructions can be longer and more irregular.

The term describing the overall interface a processor presents to software—that is, the collection of instructions, their encoding, and the supported operations—is known as the instruction set architecture. An operating system, meanwhile, is software that manages hardware and software resources and is not the instruction set itself.

So, the architecture described as using a small set of simple instructions is Reduced Instruction Set Computing (RISC).