What is an ARM processor and how does the ar­chi­tec­ture work?

An ARM processor is an energy-efficient processor based on the ARM ar­chi­tec­ture. This ar­chi­tec­ture is spe­cific­ally designed to operate with a reduced and optimised in­struc­tion set, sim­pli­fy­ing com­pu­ta­tion­al processes while in­creas­ing per­form­ance and min­im­ising energy con­sump­tion.

What sets ARM ar­chi­tec­ture apart?

The ARM ar­chi­tec­ture, ori­gin­ally developed by the British company Acorn Computers, is known for its high per­form­ance and scalab­il­ity. Thanks to its energy ef­fi­ciency, ARM pro­cessors are now found in a wide range of devices and ap­plic­a­tions, from smart­phones and tablets to modern servers.

The processor ar­chi­tec­ture is based on the principle of RISC (Reduced Instruc­tion Set Computer). By utilising this in­struc­tion set, which consists of a limited number of simple and fast in­struc­tions, ARM pro­cessors can work faster and more energy-ef­fi­ciently compared to competing products with a more extensive in­struc­tion set (CISC, like x86).

What are the key features of the ARM processor ar­chi­tec­ture?

The most notable feature of the ARM processor ar­chi­tec­ture is its energy ef­fi­ciency. Thanks to the RISC in­struc­tion set, ARM pro­cessors require less energy per com­pu­ta­tion­al operation. This makes them ideal for mobile devices that need long battery life, such as smart­phones and tablets. Energy ef­fi­ciency is further enhanced through pipelin­ing, which allows multiple in­struc­tions to be processed sim­ul­tan­eously.

Moreover, ARM pro­cessors are highly scalable and cus­tom­is­able. ARM Holdings, the company behind the ar­chi­tec­ture, licenses its designs to other companies, which then develop spe­cial­ised chips for specific ap­plic­a­tions. This allows for tailor-made solutions across various fields, ranging from simple mi­cro­con­trol­lers to complex high-per­form­ance servers. For example, Apple has been using ARM-based chips in its MacBooks since the in­tro­duc­tion of the M1 chip in late 2020.

Due to their compact and simple design, ARM chips require less space on silicon wafers and consume less energy during man­u­fac­tur­ing. This makes ARM pro­cessors more cost-effective than many al­tern­at­ives, making them es­pe­cially appealing for man­u­fac­tur­ers requiring large quant­it­ies of chips for mobile and embedded devices.

ARM pro­cessors can achieve high per­form­ance for parallel pro­cessing ap­plic­a­tions through their multi-core ar­chi­tec­ture. This is par­tic­u­larly sig­ni­fic­ant in areas like ar­ti­fi­cial in­tel­li­gence and machine learning. The ARMv9 standard, in­tro­duced in 2021, further expands the cap­ab­il­it­ies of the ARM ar­chi­tec­ture, making it well-suited for AI ap­plic­a­tions.

Ad­vant­ages of the ARM ar­chi­tec­ture at a glance

✓ Energy ef­fi­ciency: ARM chips are more energy-efficient than com­pet­it­ors thanks to the reduced in­struc­tion set.

✓ Scalab­il­ity: High scalab­il­ity ensures maximum flex­ib­il­ity.

✓ Parallel pro­cessing: Parallel com­pu­ta­tion cap­ab­il­it­ies and multi-core designs are ideal for AI ap­plic­a­tions.

✓ Cost-effective: Low energy con­sump­tion leads to af­ford­able processor solutions.

What are the most common use cases for ARM pro­cessors?

The largest market for ARM pro­cessors is in mobile devices, including smart­phones, tablets and wearables. Due to their high energy ef­fi­ciency, ARM pro­cessors are the preferred choice here. Almost all modern smart­phones use ARM pro­cessors, as they deliver long battery life along with high computing per­form­ance.

ARM pro­cessors also play a central role in embedded systems, which are in­creas­ingly used in IoT, medical devices and household ap­pli­ances. While these systems typically require only low to moderate com­pu­ta­tion­al power, long battery life and high re­li­ab­il­ity are essential.

In recent years, ARM has also gained sig­ni­fic­ant traction in server tech­no­logy. ARM servers provide an al­tern­at­ive to tra­di­tion­al x86-based servers, par­tic­u­larly in spe­cial­ised cloud ap­plic­a­tions where energy ef­fi­ciency and parallel pro­cessing are pri­or­it­ised. ARM servers are commonly found in data centres focused on high through­put and low operating costs. The use of ARM pro­cessors in dedicated servers offers clear benefits: high computing power, low power con­sump­tion and reduced cooling re­quire­ments, which can lower costs over time.

ARM pro­cessors are also becoming more popular in areas and AI ap­plic­a­tions where com­pu­ta­tions occur close to the data source. Thanks to their scalab­il­ity and ef­fi­ciency, modern ARM pro­cessors equipped with ac­cel­er­at­ors for AI cal­cu­la­tions can perform rapid analyses and make real-time decisions without needing to send data to a central data centre.

What is the ARM in­struc­tion set and pro­gram­ming model?

The ARM in­struc­tion set is designed for sim­pli­city and ef­fi­ciency, adhering to the RISC principle. Unlike more complex in­struc­tion sets (such as x86), ARM commands are largely stand­ard­ised and typically perform only one operation, which sig­ni­fic­antly sim­pli­fies hardware op­tim­isa­tion. This allows de­velopers to write clear and pre­dict­able programs that optimise both energy con­sump­tion and computing time.

Depending on the ar­chi­tec­ture, ARM pro­cessors feature either a 32-bit or 64-bit in­struc­tion set tailored to the needs of modern ap­plic­a­tions. The first 64-bit ARM in­struc­tion set, ARMv8-A, enables the pro­cessing of larger datasets and sig­ni­fic­antly expands memory ca­pa­cit­ies. The hier­arch­ic­al ARM pro­gram­ming model includes spe­cial­ised registers for specific op­er­a­tions. Fur­ther­more, pipelin­ing allows multiple in­struc­tions to be processed sim­ul­tan­eously, enhancing overall per­form­ance.