This is a job for assembly language. So you must keep it this way. In specific the Keil tools in C if they see a function with the "interrupt" keyword will take steps to auto generate the interrupt vector to the function. If you tried to make two C interrupt functions to be dispatched from the same interrupt vector you will then get a complaint from the linker that you are trying to put two sets of code at the same memory address (the linker may call this a memory overlay or conflict error).

To manage the interrupt vector table yourself you must do it yourself in ASSEMBLER. I had to do just this thing in this boot loader.

Michael Karas