Professional Embedded ARM Development

Appendix B

ARM Architecture Versions

ARM architecture versions are often a source of confusion. ARM architecture versions (designs) are written as ARMv, whereas ARM cores (the CPU) are written as ARM. Also, ARM cores do not always have the same first number as their architecture. The ARM940T is based on the ARMv4 architecture, whereas the ARM926EJ-S is based on the ARMv5 architecture. The following table lists the different ARM Architectures and their associated families.

ARCHITECTURE	FAMILY
ARMv1	ARM1
ARMv2	ARM2, ARM3
ARMv3	ARM6, ARM7
ARMv4	StrongARM, ARM7TDMI, ARM8, ARM9TDMI
ARMv5	ARM7EJ, ARM9E, ARM10E, XScale
ARMv6	ARM11
ARMv6-M	Cortex-M0, Cortex-M0+, Cortex-M1
ARMv7-A	Cortex-A5, Cortex-A7, Cortex-A8, Cortex-A9, Cortex-A12, Cortex-A15
ARMv7-R	Cortex-R4, Cortex-R5, Cortex-R7
ARMv7-M	Cortex-M3
ARMv7E-M	Cortex-M4
ARMv8-A	Cortex-A53, Cortex-A57

ARMV1

The first ARM processor was created April 26, 1985. It was targeted as a coprocessor for the BBC Micro, one of Acorn’s best-selling computers. Only a few hundred were ever made. It was originally designed to help Acorn work on the ARM2 processor but was sold to third-party developers to accustom them to the new architecture. You can imagine the thrill of using an 8-bit CPU running with a 32-bit coprocessor.

The ARM1 was a revolution for its time; it was a fully functional 32-bit processor with 26-bit addressing. It had 16 general-purpose 32-bit registers, all instructions were 32-bit, and the instruction ...