The ARM Cortex series of processors are central processing units (CPUs) designed by ARM Holdings for use in a wide range of devices from smartphones to servers. They are based on the ARM instruction set and ARM microarchitecture.
ARM Cortex-A Series
The ARM Cortex-A series processors are designed for higher-end application processors and feature out-of-order execution. Some examples include:
- ARM Cortex-A5 – An ultra low power applications processor for use in wearables and IoT devices.
- ARM Cortex-A7 – A power-efficient applications processor for mobile devices.
- ARM Cortex-A9 – A dual core applications processor found in many smartphones and tablets.
- ARM Cortex-A15 – A high performance processor capable of speeds up to 2.5GHz.
- ARM Cortex-A53 – A 64-bit power efficient mid-range processor.
- ARM Cortex-A57 – A high performance 64-bit processor for mobile and embedded devices.
- ARM Cortex-A72 – A 64-bit high performance processor capable of speeds over 2GHz.
- ARM Cortex-A73 – An evolution of the Cortex-A72 focusing on power efficiency.
- ARM Cortex-A75 – Designed for flagship mobile devices with high performance and power efficiency.
- ARM Cortex-A76 – Provides a 35% performance boost over the Cortex-A75.
The Cortex-A series is designed to provide high performance computing for devices ranging from mobile phones to servers. The processors focus on maximizing performance while maintaining power efficiency.
ARM Cortex-R Series
The ARM Cortex-R series processors are designed for high reliability applications such as automotive, industrial control systems, and networking infrastructure. Some examples include:
- ARM Cortex-R4 – A reliable real-time processor for automotive applications.
- ARM Cortex-R5 – Provides higher performance real-time processing for connected cars and ADAS.
- ARM Cortex-R7 – Offers scalable real-time performance for automotive and industrial control.
- ARM Cortex-R8 – The latest generation focused on functional safety for autonomous vehicles.
The Cortex-R series emphasizes reliability, functional safety, and real-time deterministic performance for time-critical embedded systems. Lockstep mode, ECC memory, and other features provide the necessary reliability.
ARM Cortex-M Series
The ARM Cortex-M series targets embedded microcontroller applications requiring real-time responsiveness with low power consumption. Some examples include:
- ARM Cortex-M0 – An ultra low power 32-bit MCU for simple embedded applications.
- ARM Cortex-M0+ – An evolution of the M0 with slight performance improvements.
- ARM Cortex-M1 – Designed for digital signal control applications.
- ARM Cortex-M3 – A widely used MCU providing balance between power and performance.
- ARM Cortex-M4 – Supports DSP instructions and floating point for more advanced MCU applications.
- ARM Cortex-M7 – The highest performance MCU for applications such as automotive systems.
- ARM Cortex-M23 – Designed to be the smallest ARMv8-M microcontroller.
- ARM Cortex-M33 – First ARMv8-M core designed for advanced embedded applications.
The Cortex-M series focuses on real-time performance in an efficient low power envelope. Advanced debugging and software development features make these MCUs popular for IoT edge devices.
The ARM11 family of CPUs were designed as high-performance processors for mobile devices. Some examples include:
- ARM1136JF-S – An early 1 GHz ARMv6 processor used in many smartphones.
- ARM1156T2-S – An upgraded ARM11 core found in later feature phones.
- ARM1176JZF-S – A popular processor for smartphones supporting speeds up to 1.5 GHz.
- ARM11 MPCore – A multicore ARM11 processor for mobile devices.
The ARM11 family was very successful in early smartphones. The processors provided significantly better performance compared to earlier ARM cores while maintaining low power draw.
ARM Cortex-R Series
The ARM Cortex-R series targets embedded applications requiring high reliability and functional safety guarantees. Some examples include:
- ARM Cortex-R4F – Offers lockstep functionality for safety critical systems.
- ARM Cortex-R5F -Improves determinism and real time performance over the R4F.
- ARM Cortex-R52 – A dual-core R5F for automotive applications.
- ARM Cortex-R8 – The latest R series core focused on autonomous driving.
Cortex-R processors emphasize features like lockstep cores, ECC protected memory, and guaranteed interrupt latency. This makes them suitable for automotive, industrial, and other safety-critical applications.
The ARM7 family were some of the earliest and most popular ARM processors. They powered the first wave of mobile phones and embedded devices. Some examples include:
- ARM7TDMI – The first ARM processor to include a Thumb 16-bit instruction set.
- ARM710 – An early low-power ARM core used in some of the first PDAs.
- ARM720T – Found in many early smartphones and provided better performance.
- ARM7EJ-S – A widely used ARM7 core popular in many embedded systems.
The ARM7 family paved the way for ARM’s domination of the embedded and mobile markets. Their simplicity and power efficiency drove adoption in early PDAs, phones, MP3 players, and more.
ARM Cortex-A Series
The ARM Cortex-A series targets high-performance application processing for devices like smartphones, tablets, and servers. Some examples include:
- Cortex-A5 – Ultra low power applications processor for wearables.
- Cortex-A7 – Power efficient core for entry-level mobile devices.
- Cortex-A15 – Early high performance core capable of up to 2.5GHz.
- Cortex-A53 – Popular 64-bit mid-range core for mainstream devices.
- Cortex-A57 – High performance 64-bit processor for mobile and embedded.
- Cortex-A72 – High-end 64-bit core focused on compute performance.
- Cortex-A76 – Latest core delivering 35% boost over Cortex-A75.
Cortex-A processors emphasize high performance while maintaining power efficiency. They scale from wearables up to high-end smartphones, tablets, and even servers.
ARM Cortex-M Series
The Cortex-M series are 32-bit microcontroller cores designed for real-time embedded applications. Some examples include:
- Cortex-M0 – Ultra low power MCU for simple IoT edge devices.
- Cortex-M3 – Widely used MCU providing balance of power and performance.
- Cortex-M4 – Adds DSP and floating point instructions for advanced MCUs.
- Cortex-M7 – Highest performance MCU core for applications like auto systems.
- Cortex-M23 – Smallest ARMv8-M core aiming at minimal size.
- Cortex-M33 – First ARMv8-M core with advanced embedded features.
Cortex-M cores emphasize real-time performance in an efficient low power envelope. They are popular for embedded and IoT applications requiring microcontroller functionality.
The ARM9 family were 32-bit embedded cores designed for higher performance and multimedia features. Some examples include:
- ARM920T – Early ARM9 core capable of 130 to 200+ MHz speeds.
- ARM922T – Upgrade focused on die size and cost reduction.
- ARM926EJ-S – Widely used ARM9 variant with Jazelle DBX Java acceleration.
- ARM946E-S – ARM9 upgrade with improved speed and floating point.
ARM9 cores brought higher performance, multimedia capabilities, and Java acceleration to mid-range embedded devices of the early 2000s.
ARMv8-A is the 64/32-bit architecture used by newer high-end ARM processors. Key features include:
- 64-bit registers and addressing – Supports 64-bit operating systems and large memory spaces.
- AArch64 execution state – New 64-bit only execution state for maximum performance.
- AArch32 compatibility – Supports existing 32-bit ARM code in AArch32 state.
- Advanced SIMD – NEON vector processing engine enhanced to 256-bit vectors.
- Cryptography Extensions – Dedicated instructions for encryption and decryption.
ARMv8-A provides the architecture behind cores like Cortex-A57, Cortex-A72, and others designed for 64-bit servers, high-end mobile devices, and embedded applications needing 64-bit addressing.
ARMv8-M is the architecture behind newer Cortex-M cores designed for microcontrollers. Improvements include:
- EnhancedBaselineIntegerarchitecture- Improved performance versus olderM-classcores.
- TrustZone security extensions – Optional hardware partitions for trusted execution environments.
- ARMv8 Thumb-2 instruction set – Adds more Thumb-2 encodings for better code density.
- Platform Security Architecture – Framework for implementing security at all levels.
- DSP instructions – Optional extension to enable digital signal processing.
ARMv8-M provides a trusted, real-time capable architecture to build secure IoT edge devices around Cortex-M cores like M33, M35P, and future designs.
ARMv7-A brought many improvements to ARM application processors. Some key highlights include:
- Out-of-order execution – Improved performance while maintaining backwards code compatibility.
- NEON SIMD engine – Acceleration for media, signal processing, and other parallel workloads.
- Jazelle extensions – Hardware acceleration for Java and other managed code environments.
- Thumb-2 technology – New 32-bit Thumb instruction set to complement ARM mode.
- Advanced memory system – Larger address spaces, memory prefetching, caching optimizations.
The ARMv7-A architecture powered cores like Cortex-A8 through Cortex-A15, which brought smartphone performance up to the multi-GHz range while improving power efficiency.
SecurCore is ARM’s brand for processors focused on embedded security use cases. Some examples include:
- SecurCore SC000 – Early 32-bit RISC processor for secure smart cards and SIMs.
- SecurCore SC300 – Dual-core processor for hardware security modules, TPMs, and network infrastructure.
- SecurCore SC700 – RISC-V CPU bringing scalable security to RISC-V ecosystem.
SecurCore processors target applications like secure element hardware, network security appliances, trusted platform modules, hardware security modules, and more.
ARM Instruction Sets
Some key ARM instruction sets include:
- ARM – The original 32-bit ARM instruction set that later cores are backwards compatible with.
- Thumb – A compressed 16-bit instruction set allowing better code density.
- Thumb-2 – Extended Thumb instruction set for improved performance while retaining density.
- NEON – SIMD instruction set for accelerating media, imaging, signal processing, and more.
- Jazelle – Acceleration for directly executing Java and other bytecode languages in hardware.
ARM combines RISC efficiency with features like Thumb compression, NEON acceleration, and Jazelle to create a solid architecture for embedded and mobile applications.
Big.Little is ARM’s approach to heterogeneous computing by pairing:
- Higher performance “Big” cores (like Cortex-A76).
- Lower power “Little” cores (like Cortex-A55).
The aim is to dynamically shift workload between the Big and Little cores to maximize performance and battery life. Big.Little is popular in mobile chipsets.
TrustZone is ARM’s hardware-based security architecture for creating an isolated, trusted execution environment on ARM chips. Key features include:
- Secure world vs normal world separation – Logically isolates secure and non-secure applications.
- Secure monitor mode – Allows switching between secure and non-secure states.
- Secure boot – Verifies integrity of code executed on startup.
- Trusted peripherals – Controls access to peripherals like UART, timers, and more.
TrustZone provides hardware security foundations used for Digital Rights Management (DRM), trusted execution environments, authentication, and other use cases.
ARM Server Processors
ARM-based server processors aim to provide high performance per watt advantages over traditional x86 servers. Some examples include:
- ThunderX2 – High core count processor from Cavium designed for cloud computing.
- Astra – Datacenter processor from Fujitsu with 48 ARMv8-A cores.
- Odyssey – Huawei’s ARM-based server processor targeting cloud and edge computing.
- Ampere Altra – 80-core cloud processor delivering competitive single-thread performance.
ARM server chips tend to emphasize high core counts, integrated I/O, and performance per watt efficiency for datacenter workloads. Adoption is growing for certain applications.
ARM Processors for PCs
There is growing interest in using ARM processors for laptops and desktop computers. Some examples include:
- Qualcomm Snapdragon for Windows PCs – Using Snapdragon smartphone chips for Always On PCs.
- Apple Silicon – Custom ARM chips powering latest Mac laptops and desktops.
- Nvidia Grace – ARM server processor combining ARM and Nvidia GPUs for datacenter applications.
ARM processors for PCs aim to combine laptop-class performance, battery life, and mobile connectivity in thin and light form factors. Adoption is still in early stages but could grow significantly.