How to learn ARM architecture
content to learn the arm: 
arm study's official website: www.arm.com
ARM processor architecture and
a related term 
2, A series of key technical points
3, A8 processor architecture of FIG.
Tools, operating systems and development boards
1, useful tool 
2, ARM software tool chain (toolchains)
two tool chain (comprising the GNU-gcc and ARM- comprising, armcc)
process image (Image) is generating tool chain 
1) GNU ToolChain 
Other tools
2) the Compile Toolchain to the ARM
. 3) access and configure our tool chain cross
obtaining address: www.linaro.org/downloads/
the ARM registers, and instruction set mode
1, ARM instruction set and
1) ARM instruction bit instruction set -32
2) a 16-bit Thumb instructions instruction set (high code density, but lower performance)
. 3) to support the Cortex Thumb-2-16-A and 32-bit instruction set mixing
2, CPU composition
3，处理器模式
4，寄存器
1）通用寄存器 (放通用数据，32bit）：R0 ~ R12
2）各个模式的R0 ~ R12 寄存器 与 USR 模式是共享的（除了FIQ的 R8 ~ R12是自己独用）
3）PC，CPSR是共享的
4）USR模式没有SPSR
APSR（application process status register)应用程序状态寄存器,
CPSR（ current process status register)目前程序状态寄存器，
SPSR（Saved process status register)已存储程序状态寄存器
5)例子Sample:
寄存器介绍
第8位：R0 ~ R7(Thumb指令可访问）
高8位：R8 ~ R16(Thumb指令不可访问）
目前程序状态寄存器CPSR指令格式：
5，指令流水线Pipeline
6，分支预测
