Step 4~5 STM32 internal core functions
In the first two sections, we learned what is ARM and what is the STM32 series, and the next step is to understand the internal functions of a specific STM32 microcontroller. Single-chip microcomputer is a kind of microcomputer, and its core principle is the principle of computer. The learning process is also similar for other non-ARM microcontrollers.
What we are learning is the STM32F103C8T6 single-chip microcomputer. First, we need to read the chip manual about STM32F103C8T6, not only the Chinese manual but also the original English manual. You also need to be more hands-on and practice in your studies.
Figure 3.1 STM32F103x8/xB data sheet page 1
3.1 ARM core
3.1.1 "ARM 32-bit" 
-M3, the highest operating frequency is 72MHz
This part explains what kind of computing core the microcontroller uses, and different cores will have different processing performance. The highest working frequency of 72MHz means that the working efficiency of this MCU can be changed through the internal frequency divider setting, and the maximum can only reach 72MHz. If it exceeds this setting, the MCU may be unstable or even unable to work. This sentence is to tell the developer that the operating frequency of this chip can only reach 72MHz. If a higher operating frequency is required, then other types of chips must be selected.
3.1.2 "Up to 1.25DMIPS/MHz when accessing memory with 0 wait cycles"
There is no need to waste time when reading and writing RAM and Flash during the waiting cycle of memory 0, and the reading and writing are completed in an instant. In this case, the kernel's