The Cortex family of ARM processors provides a range of solutions optimized around specific market applications across the full performance spectrum.
Cortex underlines ARM's strategy of aligning techna-ology around specific market applications and performance requirements.
The ARM Cortex family is comprised of three series, which all implement the Thumb-2 instruction set to address the increasing performance and cost demands of various markets
ARM Cortex-A Series, Aplication的意思
Applications processors for complex OS and user applications. 有MMU，這里就暗示只有A系列支持像linux這樣的系統？
Supports the ARM, Thumb and Thumb-2 instruction sets.
ARM Cortex-R Series runtime的意思，要求實時性
Embedded processors for real-time systems.
Supports the ARM, Thumb, and Thumb-2 instruction sets
ARM Cortex-M Series MCU的意思，用在汽車上，無MMU，因為MMU會帶來運行時間預測的不確定性
Deeply embedded processors
optimized for cost sensitive applications.
Supports the Thumb-2 instruction set only
它們都是Cortex的內核，是ARMv7的版本(不同於ARM7，ARM7的內核版本是ARMv4)。
Cortex-M系列的是MCU的意思
Cortex-R系列的是RunTime的意思
Cortex-A系列的是Application的意思
組合起來正好是ARM
架構一樣，根據應用在某個地方加強了一下，比如A8為了應用，流水線增為8
M系列則是用在通用的且低成本的嵌入式處理器。