RISC-V vs MIPS vs ARM

RISC-V, MIPS, and ARM are three instruction set architectures (ISAs) rooted in the Reduced Instruction Set Computing (RISC) philosophy, which favors simple, regular instructions that can be executed efficiently in a pipelined processor. While ARM has become the dominant architecture for mobile and embedded computing, RISC-V is emerging as a disruptive open-source alternative, and MIPS, once a major player, has seen its influence wane. Understanding their differences matters for hardware engineers, embedded developers, and anyone following the future of processor design.

ARM (Advanced RISC Machines) is the most commercially successful processor architecture in the world, with over 250 billion ARM-based chips shipped as of 2023. Designed by Arm Holdings (now owned by SoftBank), ARM processors power virtually every smartphone, most tablets, and an increasing number of laptops and servers. Apple's M-series chips, Qualcomm's Snapdragon, and AWS's Graviton processors are all based on the ARM ISA. ARM's licensing model is central to its success: Arm Holdings designs the ISA and reference microarchitectures, then licenses them to chip manufacturers who can either use the reference designs directly or create custom implementations. This model has created an enormous ecosystem of tools, operating systems, and software optimized for ARM.

MIPS (Microprocessor without Interlocked Pipeline Stages) was developed at Stanford University by John Hennessy in the 1980s and became one of the most important RISC architectures in the 1990s and 2000s. MIPS processors powered SGI workstations, early PlayStation consoles, and countless networking devices and embedded systems. However, MIPS Technologies struggled commercially and went through multiple ownership changes. In 2018, Wave Computing (later MIPS Technologies) acquired the MIPS architecture, and in 2019 MIPS joined the RISC-V Foundation, signaling a pivot toward RISC-V. MIPS effectively transitioned to developing RISC-V based processors, making the classic MIPS ISA largely a legacy architecture maintained for backward compatibility in existing deployments.

RISC-V is an open-source ISA that originated at the University of California, Berkeley in 2010, designed by a team including Krste Asanovic and David Patterson (co-author of the foundational textbook "Computer Architecture: A Quantitative Approach"). Unlike ARM, which requires expensive licensing agreements, the RISC-V ISA specification is freely available under permissive open-source licenses. Anyone can design, manufacture, and sell RISC-V processors without paying royalties. This has sparked enormous interest from companies seeking to avoid dependence on a single ISA vendor and from governments pursuing semiconductor sovereignty. For nations and organizations alike, RISC-V offers a path to technological autonomy that is not gated by the licensing decisions of any single corporation.

From a technical standpoint, RISC-V was designed with modern sensibilities. Its base integer instruction set is intentionally minimal (47 instructions in RV32I), with standardized extensions for multiplication (M), atomic operations (A), floating-point (F, D), compressed instructions (C), and vector processing (V). This modularity allows chip designers to implement exactly the features they need, from tiny microcontrollers to high-performance application processors. The clean-slate design avoids the accumulated complexity that older ISAs like ARM and MIPS carry from decades of backward compatibility requirements.

ARM's ecosystem advantage remains its strongest moat. Decades of software optimization, compiler support, operating system ports (Linux, Android, Windows, macOS), and developer tooling make ARM the safe choice for most commercial applications. The ARM architecture also offers advanced features like TrustZone (hardware security), SVE/SVE2 (scalable vector extensions for HPC), and a well-defined memory model that has been refined over many architecture revisions.

RISC-V's ecosystem, while growing rapidly, is still maturing. Linux kernel support is mainlined, Android support has been announced by Google, and major toolchains (GCC, LLVM/Clang) fully support RISC-V. Companies like SiFive, StarFive, and Tenstorrent are producing RISC-V application processors, while Espressif (maker of the popular ESP32) has released RISC-V based microcontrollers. China has invested heavily in RISC-V as part of its semiconductor independence strategy, with companies like Alibaba (T-Head division) and Canaan producing competitive RISC-V chips.

In the server space, ARM has made significant inroads. AWS Graviton processors power a substantial portion of Amazon's cloud infrastructure, offering better performance-per-watt than competing x86 chips. Ampere Computing produces ARM server chips used by major cloud providers. RISC-V servers are still in early stages, but companies like Ventana Micro Systems and Tenstorrent are developing high-performance RISC-V server processors targeting data center workloads.

The long-term trajectory suggests a multi-architecture world. ARM will continue to dominate mobile and embedded markets for years to come, but RISC-V is positioned to capture significant share in IoT, embedded, and specialized accelerator markets where the licensing freedom and customization flexibility of an open ISA are most valuable. MIPS, as an active ISA, has largely been absorbed into the RISC-V movement, though legacy MIPS deployments in networking equipment and industrial systems will persist for years. The competition between these architectures, along with x86, drives innovation that ultimately benefits the entire computing industry.

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