RISC-V

RISC-V is an open instruction set architecture, or ISA, used to design processors. Unlike proprietary architectures such as Arm and x86, the RISC-V instruction set can be implemented without paying a licence fee for the ISA itself, giving chip designers much greater freedom over how processors are built and customised.

What Is RISC-V?

RISC-V is a specification that describes how software talks to a processor.

That sounds rather abstract until you separate the processor into two parts.

There is the physical processor itself, containing the logic, registers, caches and other circuitry that carries out computing work. Then there is the instruction set architecture, which defines the instructions that processor understands.

Instructions cover basic operations such as loading data, storing data, performing arithmetic, comparing values and moving through a software program.

RISC-V defines this common language without dictating exactly how the processor must be physically designed.

That distinction is fundamental to the way RISC-V works.

What Does RISC-V Stand For?

RISC-V comes from Reduced Instruction Set Computer, usually shortened to RISC.

The “V” represents the fifth major RISC instruction set developed as part of the research lineage that ultimately produced RISC-V.

It is normally pronounced “risk-five”, not “risk-vee”.

The name reflects the architecture’s roots in RISC design, where processors use a relatively simple and regular collection of instructions rather than an increasingly complicated collection of specialised instructions.

What Is an Instruction Set Architecture?

An instruction set architecture is the agreed interface between software and processor hardware.

It defines things such as the instructions available to software, processor registers, data types, memory behaviour and how software interacts with the CPU at a fundamental level.

An ISA is not the same thing as the physical processor.

Two processors can look completely different internally but still execute the same software if both correctly implement the same instruction set architecture.

Is RISC-V Open Source?

RISC-V is often described as an open-source processor architecture, but that description needs a little care.

The RISC-V instruction set architecture is an open standard.

That does not mean every RISC-V processor is open source.

A company can design a RISC-V processor and keep the actual hardware implementation proprietary. Another organisation can publish an open-source RISC-V core. Both can still implement the same RISC-V instruction set.

This distinction matters because RISC-V provides openness at the architectural level without forcing every commercial chip designer to publish their processor design.

Who Owns RISC-V?

RISC-V is not controlled in the same way as a proprietary processor architecture owned by a single chip company.

The architecture originated at the University of California, Berkeley and is now governed through RISC-V International, the standards organisation responsible for developing and maintaining the RISC-V specifications.

Companies can therefore build processors around a common architecture without one semiconductor vendor owning the fundamental instruction set.

That does not remove competition. In fact, it moves more of the competition into the design of the processor itself.

RISC-V vs Arm

RISC-V and Arm are both processor architectures widely associated with efficient computing, embedded devices and increasingly powerful system-on-chip designs.

The major difference is the licensing model surrounding the instruction set.

RISC-V does not have to “kill Arm” to succeed.

Both architectures can coexist, just as different processor architectures already coexist throughout computing.

The more interesting question is whether RISC-V gives manufacturers enough technical and commercial advantage to win significant parts of markets where Arm has traditionally been the default choice.

Why Is RISC-V Important?

The importance of RISC-V comes from combining a common processor architecture with unusually broad design freedom.

A semiconductor company can build a general-purpose CPU. A small hardware developer can build a microcontroller. A cloud provider can design a specialised accelerator. A university can create an experimental processor. An equipment manufacturer can integrate a RISC-V core into a larger system-on-chip.

All can work from the same underlying ISA.

That creates the potential for a much broader processor ecosystem without requiring every participant to invent an incompatible architecture from scratch.

Why Does RISC-V Matter for IoT?

IoT is particularly well suited to RISC-V because there is no such thing as one typical IoT processor.

A battery-powered sensor might need a tiny microcontroller performing a handful of jobs while consuming almost no power.

An industrial gateway may need Linux, networking, security, local data processing and containerised applications.

An edge AI device may need specialised matrix or vector processing alongside conventional CPU cores.

RISC-V can potentially address all of these classes of device while keeping a common architectural foundation.

RISC-V in Microcontrollers

One of the most natural markets for RISC-V is the microcontroller.

Microcontrollers are small processors used to control individual functions inside products. They appear in sensors, appliances, industrial equipment, vehicles, smart-home products, meters and countless embedded systems.

These devices often need modest processing performance but face tight requirements around power consumption, cost and physical size.

RISC-V gives semiconductor designers the ability to build relatively simple processor implementations and add extensions where their application requires them.

For high-volume embedded products, even small differences in silicon area, licensing cost or power consumption can become commercially significant.

Can RISC-V Run Linux?

Yes.

RISC-V is not limited to tiny microcontrollers.

More capable 64-bit RISC-V processors can run Linux and increasingly appear in development boards, single-board computers and embedded computing platforms.

That allows RISC-V to move beyond simple control tasks into gateways, local servers, industrial computers and edge-computing systems.

IoTPortal looks at this emerging hardware market in our guide to RISC-V development boards for IoT.

What Are RISC-V Extensions?

RISC-V was designed as a modular architecture.

A processor does not have to implement every possible capability. Designers can begin with a base instruction set and add standard extensions for features required by a particular processor.

These can cover capabilities such as integer multiplication and division, floating-point mathematics, atomic operations, compressed instructions and vector processing.

There is also scope for specialised instructions where manufacturers need hardware optimised for particular workloads.

That modularity is one reason RISC-V is attractive for embedded and IoT hardware, where adding unnecessary processor functionality can waste silicon area, power and money.

Does RISC-V Mean Cheaper Chips?

Not automatically.

Removing an ISA licensing cost does not remove the cost of actually designing, verifying, manufacturing and supporting a processor.

Modern silicon development is enormously expensive.

A processor still needs engineering work, verification, physical implementation, fabrication, testing, software tools, operating-system support and long-term maintenance.

RISC-V changes one part of the economic model. It does not make semiconductor development free.

Is RISC-V More Secure?

RISC-V is not automatically more secure or less secure than another processor architecture.

Security depends on the design of the processor, firmware, operating system, boot process, memory protection, cryptography and the wider device around it.

The open nature of the ISA can help researchers understand the architecture and allows manufacturers to build specialised security features, but a badly designed RISC-V device can still be insecure.

The sensible way to view RISC-V is as an architectural foundation on which secure or insecure systems can both be built.

What Are the Limitations of RISC-V?

The biggest challenge facing RISC-V is maturity.

Arm and x86 have enormous software, tooling and hardware ecosystems built over decades.

RISC-V is developing quickly, but developers can still encounter differences in toolchain maturity, driver support, operating-system compatibility, hardware availability and commercial support depending on the processor they choose.

Fragmentation also needs careful management.

The ability to customise processors is valuable, but software ecosystems work best when hardware remains sufficiently standardised that applications do not have to be rewritten for every chip.

This is why formal specifications, standard extensions and compatibility testing matter as the architecture grows.

RISC-V and Single-Board Computers

RISC-V is increasingly visible in development boards and single-board computers.

These products give developers a practical way to experiment with the architecture without designing their own hardware.

For IoT, they are particularly useful for testing Linux support, embedded applications, networking, protocol conversion, local processing and edge-computing workloads.

The market is still considerably less mature than Raspberry Pi and established Arm SBC ecosystems, but the hardware is improving quickly.

Some processors are also beginning to combine different architectures on the same system-on-chip. The Allwinner A733, for example, combines conventional application processing with a RISC-V core for specific workloads.

Will RISC-V Replace Arm?

It is possible that RISC-V will take a significant share of markets currently dominated by Arm, particularly in microcontrollers, embedded systems and specialised processors.

That is not the same as saying Arm will disappear.

Arm has an enormous installed base, mature software support, experienced developers and a highly developed commercial ecosystem.

RISC-V does not need to replace Arm everywhere to become one of the world’s major processor architectures.

The more plausible outcome is a computing market where manufacturers have another serious architectural choice.

Why Is RISC-V Becoming Important Now?

For decades, most organisations designing connected products had relatively few mainstream processor architectures to choose from.

At the same time, computing has become increasingly specialised.

Tiny battery-powered sensors, AI accelerators, industrial controllers, automotive systems and cloud processors have very different requirements.

RISC-V arrives at a point when manufacturers increasingly want processors tailored around particular workloads rather than one general-purpose design forced into every application.

IoT amplifies that trend because the range of connected devices is so broad.

For a wider look at the hardware behind connected systems, visit the IoT hardware section.

RISC-V Frequently Asked Questions

Related IoT Terms and Guides

RISC-V sits at the intersection of semiconductor design, embedded computing and the IoT edge. These IoTPortal resources provide useful background and further reading.

RISC-V Glossary Definition