Difference Between RISC and CISC

RISC vs CISC

RISC (Reduced Instruction Set Computing) and CISC (Complex Instruction Set Computing) are two computer architectures that are predominantly used nowadays. The main difference between RISC and CISC is in the number of computing cycles each of their instructions take. With CISC, each instruction may utilize a much greater number of cycles before completion than in RISC.

The reason behind the difference in number of cycles utilized is the complexity and goal of their instructions. In RISC, each instruction is only meant to achieve a very small task. So if you want a complex task done, then you need a lot of these instructions strung together. With CISC, each instruction is similar to a high level language code. You only need a few instructions to get what you want as each instruction does a lot.

In terms of the list of available instructions, RISC has the longer one over CISC. This is because each small step may need a separate instruction, unlike in CISC where a single instruction would already cover multiple steps. Although CISC may be easier for programmers, it also has its downside. Using CISC may not be as efficient as when you use RISC. This is because inefficiencies in the CISC code will then be used again and again, leading to wasted cycles. Using RISC allows the programmer to remove unnecessary code and prevent wasting cycles.

The previous differences may make sense to those who are technologically inclined. But for most people, it would be gibberish. To make it easier to understand, it is better to look at where the two are being used. CISC has managed to gain an early lead in computing with the dominance of Intel’s x86 architecture, which is the basis for all other modern computer architectures. In contrast, RISC has managed to work its way into portable devices like smartphones, tablets, GPS receivers, and other similar devices. ARM is one of the notable RISC architectures used in these devices. The higher efficiency of the RISC architecture makes it desirable in these applications where cycles and power are usually in short supply.

Summary:

1. CISC instructions utilize more cycles than RISC
2. CISC has way more complex instructions than RISC
3. CISC typically has fewer instructions than RISC
4. CISC implementations tend to be slower than RISC implementations
5. Computers typically use CISC while tablets, smartphones and other devices use RISC

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