What Is RISC?

A Reduced Instruction Set Computer is a type of microprocessor architecture that utilizes a small, highly-optimized set of instructions rather than the highly-specialized set of instructions typically found in other architectures. RISC is an alternative to the Complex Instruction Set Computing (CISC) architecture and is often considered the most efficient CPU architecture technology available today.

With RISC, a central processing unit (CPU) implements the processor design principle of simplified instructions that can do less but can execute more rapidly. The result is improved performance. A key RISC feature is that it allows developers to increase the register set and increase internal parallelism by increasing the number of parallel threads executed by the CPU and increasing the speed of the CPU's executing instructions. ARM, or “Advanced RISC Machine” is a specific family of instruction set architecture that’s based on reduced instruction set architecture developed by Arm Ltd. Processors based on this architecture are common in smartphones, tablets, laptops, gaming consoles and desktops, as well as a growing number of other intelligent devices.

Why Is RISC Important?

RISC provides high performance per watt for battery operated devices where energy efficiency is key. A RISC processor executes one action per instruction. By taking just one cycle to complete, operation execution time is optimized.

Because the architecture uses a fixed length of instruction, it’s easier to pipeline. And because it lacks complex instruction decoding logic, it supports more registers and spends less time on loading and storing values to memory.

For chip designers, RISC processors simplify the design and deployment process and provide a lower per-chip cost due to the smaller components required. Because of the reduced instruction set and simple decoding logic, less chip space is used, fewer transistors are required, and more general-purpose registers can fit into the central processing unit.

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