I'm not going to go get all involved in your project Tang but it seems you have a learning curve to climb. I would strongly suggest you get off the bandwagon of using C for your boot loader. Use assembler for that.

Do be aware that there are those out there, including me, that will say that you are in dangerous territory trying to use C on an embedded MCU project when you know little or nothing about the use of the assembly language on that MCU. When you start trying to work with boot loaders, relocated interrupt vector tables and StartUp code it is essential that you be very very familiar with the assembler language.

I would strongly suggest that you take a different approach to your project. Instead of trying to learn what you are doing by trying to get answers to the the detailed assembler parts from members on this discussion board you should instead fully learn assembly language first. Read a book or some tutorials, make some programs in assembler or even possibly take a course of training. After you start to master that then go to a compiler vendor web site such as the Keil one and use their knowledge base to link to and gather all information you can learn about relocated interrupt vector tables, how startup code works and what it does. Armed with this type of information you would be in a position to use code similar to what Erik showed you or to understand how the code posted here works.

You may also want to reference these previous discussions if you had not already searched here at 8052.com.

http://www.8052.com/forum/read/49879
http://www.8052.com/forum/read/74433
http://www.8052.com/forum/read/90590


Michael Karas