Learn ARM development (4)

I have learned the general structure of the CPU. Of course, I have learned the structure of 80X86 before, so I can imagine what a RISC computer is like. If you have not studied "Microcomputer Principles", it is best to take a look at it, or look at the RISC CPU design, that is, the design of Loongson. There are many design documents about Loongson in Tsinghua University, and these are the functions of the CPU.

Why do we need to learn assembly? Aren't most programs written in C? Yes, most embedded software is currently developed in C. In fact, learning assembly is to better understand the processing of the CPU. This is just for understanding, for a deeper understanding, rather than using it to develop most applications. Of course, it is also useful. For example, programs like BOOTLOADER cannot be completed without assembly. There are also those with special instructions that cannot be written without assembly. At present, I learn assembly just to write BOOTLOADER. I don't learn it for the sake of learning it all, but take out the source code of BOOTLOADER, understand the assembly from it, understand other people's BOOTLOADER, or can modify its assembly, and that is considered to be the learning is complete, and there is no need to memorize and understand every instruction. Only the instructions in the BOOTLOADER are read and understood. After reading a BOOTLOADER, it is equivalent to completing the learning of assembly, and there is no need to write any new assembly by yourself. As long as you can modify the existing BOOTLOADER, you have completed the task.

Next time, I will look at the source code of U-BOOT. Of course, it is based on the BOOTLOADER of S3C44B0.