On reset what happens in embedded system?

Question

I have a doubt regarding the reset due to power up:

1.As i know that microcontroller is hardwired to start with some particular memory location say 0000H on power up

Answer 1

Depends completely on the controller/embedded system you use. The ones I've used in game development have the IP point at a starting address in RAM. The boot strap code supplied from the compiler initializes static/const memory, sets the stack pointer, and then jumps execution to a main() routine of some sort. Older systems also started at a fixed address, but you manually had to set the stack, starting vector table, and other stuff in assembler. A common name for the starting assembler file is CRT0.s for the stuff I've done.

So 1. You are correct. The microprocessor has to start at some fixed address. 2. The ISR can be supplied by the manufacturer or compiler creator, or you can write one yourself, depending on the complexity of the system in question. 3. The stack and initial programmer counter are usually handled via some sort of bootstrap routine that quite often can be overriden with your own code. See above.

Last: The steps will depend on the chip. If there is a power interruption of any sort, RAM may be scrambled and all ISR vector tables and startup code should be rewritten, and the app should be run as if it just powered up. But, read your documentation! I'm sure there is platform specific stuff there that will answer these for your specific case.