Processor Architecture & CPU Internalsfoundational
List some ARM cores. For embedded use, which cores were most commonly used in the past? now?
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A non-exhaustive list of ARM cores, by family
- Classic / legacy: ARM7TDMI (ARMv4T); ARM9 — ARM920T/ARM922T are ARMv4T, while ARM9E (e.g. ARM926EJ-S) is ARMv5TE; ARM11 (ARMv6).
- Cortex-M (microcontroller / "M" profile, deterministic, no MMU):
- Cortex-M0 / M0+ (ARMv6-M) — ultra-low-power, smallest, M0+ adds fast I/O and optional MPU.
- Cortex-M1 (FPGA-targeted).
- Cortex-M3 (ARMv7-M) — the workhorse 32-bit MCU core.
- Cortex-M4 (ARMv7-M + DSP, optional single-precision FPU) — DSP/control.
- Cortex-M7 (ARMv7-M, superscalar, caches, SP/DP FPU) — high-performance MCU.
- Cortex-M23 / M33 / M35P / M55 / M85 (ARMv8-M) — add TrustZone security; M55/M85 add Helium (MVE) vector for ML/DSP.
- Cortex-R (real-time, "R" profile — high performance with deterministic, often lockstep/safety): Cortex-R4, R5, R7, R8, R52 — used in storage controllers, automotive safety, modems.
- Cortex-A (application, "A" profile — MMU, runs Linux/Android/iOS): Cortex-A7, A8, A9, A15, A53, A57, A72, A76, A78, X-series, etc., plus the AArch64 (ARMv8-A/ARMv9-A) generations.
- SecurCore (smartcard), and Neoverse (server/infrastructure).
Most common embedded cores — past vs. now
- In the past: For deeply embedded 32-bit work, the ARM7TDMI was hugely dominant in the late 1990s/2000s (used in countless MCUs and SoCs), followed by ARM9 (e.g., ARM926EJ-S) for higher-end embedded/Linux-capable devices. These predate the Cortex naming.
- Now: For microcontroller-class embedded, the Cortex-M series dominates — especially Cortex-M0+ and Cortex-M4 for mainstream/low-power designs, Cortex-M3 as the established general-purpose core, and Cortex-M7 where higher performance is needed; newer secure/ML designs increasingly use the ARMv8-M Cortex-M33 (TrustZone) and M55/M85 (Helium). For embedded real-time/safety, Cortex-R (e.g., R5/R52). For embedded Linux/application-class devices (gateways, smart displays, phones, wearables), the Cortex-A family (e.g., A7/A53 historically, modern A55/A7x and AArch64 cores today).