Far as I've seen on systems with MMU's generally you get page fault. And then the OS handles that and issues a seqfault. Which is what happens usually when you start trying to poke at random addresses.
On an ARM Cortex, if you try and read a null pointer you get the top of stack address. Least on my machine/compiler. If you try and write, then you get a bus fault. Beacuse flash memory is mapped to that address.
On an AVR, I think reading gives you the reset vector. And write to address 0 is useally a nop. I think with some magic though you can write to that page of flash.
On an ARM Cortex, if you try and read a null pointer you get the top of stack address. Least on my machine/compiler. If you try and write, then you get a bus fault. Beacuse flash memory is mapped to that address.
On an AVR, I think reading gives you the reset vector. And write to address 0 is useally a nop. I think with some magic though you can write to that page of flash.
So yeah. Kinda depends.