Hi all, I am using uVision3 to program my STR710 MCU in C langue. For evaluation purpose I am running from SRAM. In the uVision-project there is a file named: Startup.s. In this file the basic settings of the STR710 to operate are done. In this file also all the interrupts are initialised. I have all the IRQ's handlers working. Also the 2 FIQ's I have working. The problem is that I do not get the Reset, Undefined, PAbt and DAbt handlers working. I have written the handler functions in my program but they are not entered. In my C program I have the folowing handler: void Undef_Handler (void) __irq { RCCU->CCR |= 0x808; // Program counter corrupted jump to unknown memory location , system reset RCCU->SMR |= 0x02; } I am trying to test the handler this way. During debug I can change the PC(PC $ option in register window during debugging)in uVision.(am I allowed to?) I set it to 0x40020000(flash). On this location there are only 0xFFFFFFFF filled registers. With the MCU processing 0xFFFFFFFF an undefined exception should find place. The program should enter the Undef_handler, but it does not. The program just crashes. Does someone know how the handle the Reset, Undefined, PAbt and DAbt handlers in a C progam? Regards, Erik