CISC allows a computer to do more in a single instruction cycle, while RISC allows for simpler programming. Generally speaking, RISC requires more clock cycles to complete the same instruction in CISC but can do so more efficiently (energy-wise), making them ideal for mobile applications. While x86/x64 remains the dominant architecture in the heavy processing market, ARM may face serious competition from a new processor architecture, RISC-V.

ARM and RISC-V are instruction set architectures, or ISAs. The ISA is the foundation of a processor and is the most fundamental and basic component of any CPU. Both ISAs are reduced instruction set computer (or RISC) designs, meaning the base instructions the CPU has access to are inherently simple but ideally fast to calculate. The ‘R’ in ARM actually stands for RISC (though ARM is no longer treated as an acronym), so in this sense the two ISAs are similar.